The Torah is a handwritten parchment scroll which the Jewish religion uses as religous text. It describes the rules for Jewish society and contains stories and poems. The books of the Torah include Genesis, Exodus, Leviticus, Numbers and Deuteronomy.
The Torah is what Tevye longs to study for hours a day and the Rabbi and Mendel successfully study for hours a day. This is indicated in an early scene where Tevye claims quotes incorrectly and Mendel corrects him.
Moskowitz, S. (n.d.) Torah Cannot be Torah Without Us. Retrieved from: https://reformjudaism.org/jewish-holidays/shmini-atzeret-and-simchat-torah/torah-cannot-be-torah-without-us
My Jewish Learning. (n.d.) The Torah. Retrieved from: https://www.myjewishlearning.com/article/the-torah/