(1) If his offering is a sacrifice of shelamim— If he offers of the herd, whether a male or a female, he shall bring before the Eternal one without blemish. (2) He shall lay his hand upon the head of his offering and slaughter it at the entrance of the Tent of Meeting; and Aaron’s sons, the priests, shall dash the blood against all sides of the altar. (3) He shall then present from the sacrifice of shelamim, as an offering by fire to the Eternal, the fat that covers the entrails and all the fat that is about the entrails; (4) the two kidneys and the fat that is on them, that is at the loins; and the protuberance on the liver, which he shall remove with the kidneys. (5) Aaron’s sons shall turn these into smoke on the altar, with the burnt offering which is upon the wood that is on the fire, as an offering by fire, of pleasing odour to the Eternal. (6) And if his offering for a sacrifice of shelamim to the Eternal is from the flock, whether a male or a female, he shall offer one without blemish. (7) If he presents a sheep as his offering, he shall bring it before the Eternal (8) and lay his hand upon the head of his offering. It shall be slaughtered before the Tent of Meeting, and Aaron’s sons shall dash its blood against all sides of the altar. (9) He shall then present, as an offering by fire to the Eternal, the fat from the sacrifice of shelamim: the whole broad tail, which shall be removed close to the backbone; the fat that covers the entrails and all the fat that is about the entrails; (10) the two kidneys and the fat that is on them, that is at the loins; and the protuberance on the liver, which he shall remove with the kidneys. (11) The priest shall turn these into smoke on the altar as food, an offering by fire to the Eternal. (12) And if his offering is a goat, he shall bring it before the Eternal (13) and lay his hand upon its head. It shall be slaughtered before the Tent of Meeting, and Aaron’s sons shall dash its blood against all sides of the altar. (14) He shall then present as his offering from it, as an offering by fire to the Eternal, the fat that covers the entrails and all the fat that is about the entrails; (15) the two kidneys and the fat that is on them, that is at the loins; and the protuberance on the liver, which he shall remove with the kidneys. (16) The priest shall turn these into smoke on the altar as food, an offering by fire, of pleasing odour. All fat is the Eternal's. (17) It is a law for all time throughout the ages, in all your settlements: you must not eat any fat or any blood.

'Peace-Offering' Jewish Encyclopedia
There are three kinds of peace-offering: (1) the thank-offering (todah); (2) the votive-offering (neder); and (3) the free-will offering (nedava). The thank-offering is a response to acts of divine beneficence; the votive and the free-will sacrifices are connected with the expectation of benefit; but the significance of the thank-offering is wider than that of the other two. The votive offering is prompted by a feeling of gratefulness at the fulfilment of a petition; while the free-will sacrifice, which has the character of complete voluntariness, has its origin not so much in the gratitude elicited by a happy experience as in the spontaneous motive of piety.
שלמים PEACE-OFFERINGS — They are so called because they bring peace (שלום) into the world. Another explanation is: they are called שלמים because through them there is “peace” (harmony and lack of envy) to the altar, to the priests and to the owners.
But isn’t it taught: With regard to the verse: “And if his offering be a sacrifice of peace offerings [shelamim]” (Leviticus 3:1), Rabbi Shimon says: The offering is called shelamim to teach that when a person is whole [shalem] he brings his offering, but he does not bring it when he is an acute mourner. From where is it derived to include that an acute mourner does not bring even a thanks offering? I include the thanks offering because it is consumed in a state of joy, like a peace offering.
'Peace-Offering' Jewish Encyclopedia
Kurtz ("Das Mosaische Opfer," pp. 129-154, Mitau, 1842; idem, "Der Alttestamentliche Opfercultus," ib. 1862) maintains that means "to be perfect," "to make perfect." The sacrifice, therefore, has for its purpose a "restitutio integra," a rehabilitation of the person. Besides, divine benefits cause one to feel that the grace received is undeserved. God shows by His gracious deeds that He maintains His part of the covenant. The thank-offering is to restore the right relation under the consciousness that man on his part has been derelict. The free-will offering and the vow-offering are always mentioned together: their rituals, too, are identical in essential points as differing from the thank-offering. "Peace-offering" is a term covering the different kinds of sacrifices, but it is a thank-offering.
Kalisch ("A Historical and Critical Commentary on the Old Testament, Book of Leviticus," part i., pp. 241-249, London, 1867) says that the shelamim were "safety-offerings." They were connected with what was deemed essential to happiness and a secure existence. The rendering "peace-offering" is vague, and is admissible only on condition that peace is understood to be equivalent to safety, and also that the frame of mind in which the sacrifice is offered is considered. The explanation as "praise-offering,"he says, is not plausible, viz., that God, the priest, and the offerer, on receiving a portion of it, conclude a mutual alliance. The social element connected with the shelamim intimates that it is of later origin than the rest; for it presupposes a degree of legal and political organization considerably in advance of primitive times. Fatness seems to be the leading characteristic of the offering; and fatness is typical of abundance and prosperity. During long periods, also, peace-offerings were employed for the ratification of solemn covenants, treaties, and alliances; and the common meal which followed on such occasions, according to Eastern notions and customs, was peculiarly appropriate.