Learn Spanish (Spain): Invitamos al vecino a la fiesta. - We invite the neighbor to the party.

This is the personal a in action! In Spanish, when the object of a verb is a specific person (like a neighbor), you must put the word a before it. Because vecino is masculine and uses the word el (the), the words a and el combine into the single word al.

There are two a words in this sentence (one inside al and one in a la). Do they do the same job?

They look similar but do completely different jobs! The first one (inside al) is the personal a, which is a grammar rule for actions done to people and doesn't translate to English. The second a in a la fiesta is a normal preposition that simply means 'to' (to the party).

Where is the word for 'we' in this sentence?

In Spanish, the 'we' (nosotros) is built right into the verb. The -amos ending on invitamos tells you exactly who is doing the inviting, so you can just drop the pronoun nosotros entirely.

Wait, doesn't invitamos also mean 'we invited' in the past tense?

Yes, great catch! For regular verbs ending in -ar (like invitar), the 'we' form is exactly the same in both the present tense and the simple past tense. In real conversations, you figure out which one is meant from context clues like 'yesterday' or 'every day'.