Wrong english translation. Nos olvidamos means we forget ourselves!
What was the english translation?
It seems to be “We forgot”.
It’s right, but it is another out of context phrase, to say that you need a previous phrase saying what was that thing that later you say you forgot.
Anyway, the Spanish verb is reflexive, so “We forgot ourselves” would be something like “Nos olvidamos de nosotros (mismos).”