Learn Italian: I nonni arrivano oggi. Li aspettiamo alla stazione. - The grandparents arrive today. We are waiting for them at the station.

In Italian, short object pronouns like li (meaning "them") usually go directly before the conjugated verb. While in English we say "we are waiting for them", the Italian structure is literally "them we wait for" (li aspettiamo).

How do we know to use li instead of le for "them"?

The pronoun must match the gender and number of the noun it replaces. Here, it refers back to i nonni (the grandparents). Since nonni is a masculine plural noun, you use the masculine plural pronoun li. If you were waiting for le nonne (the grandmothers), you would use le.

Why isn't there a word for "for" in Li aspettiamo?

The Italian verb aspettare already means "to wait for" all by itself. You never need to add an extra preposition for "for". Therefore, aspettiamo means "we wait for", and putting li in front makes it "we wait for them".

Why do we use alla instead of just a before stazione?