Learn Spanish (Latin America): Yo veía el tranvía en la avenida.

Ver (to see) is one of only three irregular verbs in the imperfect tense! A regular -er verb would drop the ending to add -ía, which would make vía. But ver keeps its e, making it veía.

The translation says "I used to see." Could veía also mean "I was seeing"?

Yes, it absolutely can. The imperfect tense covers both past habits ("used to see") and ongoing past actions ("was seeing"). In this specific sentence, "used to see" is the most natural translation for describing a routine from the past.

Why is it el tranvía? Shouldn't words ending in -a be feminine?

Usually, yes! But tranvía (tram) is one of those rule-breaking masculine words, so it uses el. You might remember other common exceptions from earlier lessons, like el problema or el mapa.

Why do both veía and tranvía have an accent mark on the letter i?

The accent mark prevents the i and the a from blending into a single syllable. It tells you to pronounce the vowels separately with the stress on the i, sounding like "ee-ah" instead of "ya".