Learn Hardcore Serbian: Potrošili smo novac.

So literally it is something like spent + we-have/we-are, but in normal English you simply translate it as we spent or we have spent, depending on context.

Because potrošiti is a perfective verb, the sentence usually suggests a completed action: We spent the money / We have spent the money.

Why is there no word for we?

In Serbian, the subject pronoun is often left out because the verb already shows who is doing the action.

Here, smo tells you it is we.

So:

Potrošili smo novac. = We spent the money.
Mi smo potrošili novac. also means We spent the money, but mi adds emphasis, like we in particular.

Serbian does this very often, so leaving out mi is completely normal.

Why is it potrošili smo, not smo potrošili?

This is because is a in Serbian. Clitics usually go in the of the sentence or clause.