Learn Finnish: Me muistamme hänet.

Hänet is the accusative (object) form of hän (he/she). Because "her" is the target of the action (the person being remembered), it needs this specific object form. For personal pronouns, the accusative form always ends in -t.

Can hänet also mean "him"?

Yes! Just like the basic pronoun hän, the object form hänet is completely gender-neutral. It translates to "him" or "her" depending entirely on the context of the conversation.

Why doesn't the object end in -n, like regular nouns usually do?

Personal pronouns have their own special rule for the accusative (object) case. While a regular noun might take an -n ending to show it is a whole object, personal pronouns always take a -t ending. This is why we use hänet instead of hänen (which is actually the form meaning "his/her").

How does the verb muistaa change to become muistamme?

The basic verb is muistaa (to remember). To make it match the subject me (we), you add the "we" ending -mme to the verb, giving us muistamme.