Complete Passuk
וַיִּטַּ֞ע יְהֹוָ֧ה אֱלֹהִ֛ים גַּן־בְּעֵ֖דֶן מִקֶּ֑דֶם וַיָּ֣שֶׂם שָׁ֔ם אֶת־הָֽאָדָ֖ם אֲשֶׁ֥ר יָצָֽר׃
Chabad / Judaica Press
Core Textגַּן בְּעֵדֶן מִקֶּדֶם — מִלְּבַד שֶׁגַּן עֵדֶן נִבְרָא קֹדֶם שֶׁנִּבְרָא הָעוֹלָם.
English: “A garden in Eden from the east (mikedem)” — besides [its location], the Garden of Eden was created before the world was created.
On the daf / in context: Among the things created before the six days, Gan Eden is listed; “mikedem” is read as “from before.”
Type of Learning: Custom (pre-creation of Gan Eden)
What Is Learned: Gan Eden was created prior to the creation of the world.