Breakdown of Eu não vou pelas escadas.
eu
I
não
not / no
ir
to go
pelo
through the (m.sg, pela, pelos, pelas)
Questions & Answers about Eu não vou pelas escadas.
Where does the word pelas come from?
Pelas is a mandatory contraction. It combines the preposition por (which can mean by, through, or via) and the feminine plural word for the, which is as. Because escadas (stairs) is feminine and plural, they merge to become pelas.
The English translation says take the stairs, but doesn't vou mean go?
Exactly! A literal translation of this sentence is I do not go by the stairs. While in English you take the stairs, in Portuguese you use the verb ir (to go) combined with the preposition por (by or via) to express the exact same action.
Why is escadas plural here? Could I just say escada?
Just like in English, Portuguese typically uses the plural escadas to refer to a flight of stairs or a staircase in a building. The singular escada exists and is sometimes used for a staircase, but it is also the specific word for a ladder.