Two is a noun when it refers to the number two as in two plus two is four. The word two is derived from the Old English words twā (feminine), tū (neuter), and twēġen (masculine, which survives today in the form twain).
From Middle English two, twa, from Old English twā, feminine and neuter of twēġen (whence twain), from Proto-West Germanic *twai-, from Proto-Germanic *twai, from Proto-Indo-European *dwóh₁.
Two is a whole number that's greater than one, but less than three. If you found one fuzzy mitten and then your friend gave you another one, you would have two mittens — perfect for your two hands.
Two (noun): symbol or word representing the number after one and before three in the decimal system. The term "two" is widely recognized and used across various contexts, from simple arithmetic to cultural idioms.
Idioms in two, into two separate parts, as halves: The cake was cut in two. Idioms put two and two together, to reach the correct and obvious conclusion: Putting two and two together, they came up with the murderer.