Learn Hardcore Spanish (Spain): Vimos al demonio ayer.

So it means we saw and tells you the action is viewed as completed in the past. In other words, the seeing happened yesterday and is treated as a finished event.

The full preterite of ver is:

vi — I saw
viste — you saw
vio — he/she/it saw
vimos — we saw
visteis — you all saw (Spain)
vieron — they/you all saw

Why isn’t nosotros written in the sentence?

Spanish often drops subject pronouns because the verb ending already tells you who the subject is.

Here, vimos already means we saw, so nosotros is not necessary.

You could say:

Nosotros vimos al demonio ayer.

But it usually sounds more natural to leave nosotros out unless you want to add emphasis or contrast, such as:

Nosotros vimos al demonio, pero ellos no.
We saw the demon, but they didn’t.

Why do we say al instead of a el?