אֵין רֵאשִׁית אֶלָּא בִּכּוּרִים, שֶׁנֶּאֱמַר (שמות כג, יט): רֵאשִׁית בִּכּוּרֵי אַדְמָתְךָ וגו'.
When we see the word Reishit, it is talking about your first fruits, as it says (Exodus 23:19): "The beginning (Reishit) of the fruits of the land."
וְהַתּוֹרָה אָמְרָה בְּרֵאשִׁית בָּרָא אֱלֹהִים. וְאֵין רֵאשִׁית אֶלָּא תּוֹרָה, הֵיאַךְ מָה דְּאַתְּ אָמַר (משלי ח, כב): ה' קָנָנִי רֵאשִׁית דַּרְכּוֹ.
"Through the Reishis, Hashem created [the heavens and the earth]," and Reishis means Torah, as it says in the book of Proverbs -
(22) “The LORD created me at the beginning (Reishit) of His course as the first of His works of old."
And we can say, that the intention here can be learned from the following teaching from the sages -
כׇּל הַמֵּבִיא דּוֹרוֹן לְתַלְמִיד חָכָם כְּאִילּוּ מַקְרִיב בִּכּוּרִים
Whoever brings a gift to a Torah scholar, it is as though he has presented first fruits.
And behold, just like Torah and the first fruits are called Reishit, so too the children of Israel are called Reishit! As is taught by the sages of Israel -
אָמַר רַבִּי בֶּרֶכְיָה שָׁמַיִם וָאָרֶץ לֹא נִבְרְאוּ אֶלָּא בִּזְכוּת יִשְׂרָאֵל, דִּכְתִיב (בראשית א, א): בְּרֵאשִׁית בָּרָא אֱלֹהִים, וְאֵין רֵאשִׁית אֶלָּא יִשְׂרָאֵל
Rebbe Berchaya says, the heavens and the earth were only created in the merit of Israel, as its written - "In the beginning (Bereishit) G-D created"And there is no (Reishit) outside of Israel, as we can see below -
(ג) קֹ֤דֶשׁ יִשְׂרָאֵל֙ לַיהֹוָ֔ה רֵאשִׁ֖ית תְּבוּאָתֹ֑ה כׇּל־אֹכְלָ֣יו יֶאְשָׁ֔מוּ רָעָ֛ה תָּבֹ֥א אֲלֵיהֶ֖ם נְאֻם־יְהֹוָֽה׃ {פ}
(3) Israel was holy to the LORD, The first fruits (Reishit) of His harvest. All who ate of it were held guilty; Disaster befell them —declares the LORD.
Bikurim - first fruits
Yisrael - Israel
Torah - the Torah
This alludes to the reality that everyone from Israel must either be a Yissachar or Zevulun, which is either learning Torah, or supporting those that learn Torah, and both of those categories are called Reishit, as the study of Torah and the supporting of the study of Torah is both called Reishit, because we already know that supporting Torah study, is as if you are learning it yourself!