Learn Portuguese (Portugal): Nós caminhamos pela ponte.

The word pela is a contraction of the preposition por and the feminine word for "the", which is a. When talking about movement across, through, or over a surface, Portuguese uses por. So por + a becomes pela.

How do we know to use pela instead of pelo?

It depends on the gender of the noun that follows it. The word for bridge, ponte, is feminine. Even though it ends in an "e" rather than an "a", it is a feminine word, so we must use the feminine contraction pela.

The dictionary says por means "for" or "by". Why does it mean "over" here?

The preposition por is very flexible. When used with motion verbs like caminhar (to walk), it describes the path or route taken. Depending on the context in English, it can translate to "over", "through", "across", or "along".

Is it okay to drop the word Nós and just say Caminhamos pela ponte?

Yes! Because the verb ending -amos in caminhamos specifically means "we walk", the pronoun Nós is completely optional. Portuguese speakers often drop these pronouns unless they want to add emphasis.