Learn Portuguese (Portugal): Nós fizemos muito barulho ontem.

Fizemos is the simple past tense (Pretérito Perfeito) of fazer (to do / to make) for the "we" form (nós). Fazer is an irregular verb, so its root changes from faz- to fiz- in the past tense. If you used fazemos, that would be the present tense meaning "we make".

Why is it muito and not muitos?

The word muito translates to "a lot of" or "much" here. It acts as a describer that must match its noun. Because barulho (noise) is a masculine, singular word, muito also stays in its masculine, singular form. You would only add an "-s" if the noun was plural.

Can I drop the word Nós from this sentence?

Yes, you can. In Portuguese, the verb ending in fizemos already tells the listener that the subject is nós (we). Saying just Fizemos muito barulho ontem is completely correct and very common in everyday speech.