In Orach Chaim 186:1, the Arukh haShulchan discusses whether in Birkhas haMazon women should say “וְעַל בְּרִיתְ֒ךָ שֶׁחָתַֽמְתָּ בִּבְשָׂרֵֽנוּ וְעַל תּוֹרָתְ֒ךָ שֶׁלִּמַּדְתָּֽנוּ – for Your covenant which You sealed in our flesh; for Your Torah which You taught us;”…

The Jewish People are subject to two covenants with Hashem: Beris Avos, and Beris Sinai. That is what this line is referring to — the Beris seals in our flesh is Beris Avos, and the Torah is part of Beris Sinai. While women aren’t obligated in either Milah or Torah study, they are members of both covenants.