Learn Italian: La minoranza è piccola, ma è molto rumorosa. - The minority is small, but it is very noisy.

La minoranza (the minority) is a collective noun. In Italian, grammar is very strict about agreement: because the noun itself is feminine and singular, all verbs and adjectives connected to it must also be feminine and singular (è, piccola, rumorosa). You cannot use plural forms just because the group contains multiple people.

Why is it molto rumorosa instead of molta rumorosa to match the feminine noun?

Here, molto is acting as an adverb meaning "very," and adverbs never change their endings. Molto only changes its ending to agree with a noun when it acts as an adjective meaning "a lot of" or "many" (for example, molta gente meaning "a lot of people").

Where is the word for "it" in the second half of the sentence (ma è molto rumorosa)?

Italian drops subject pronouns when it is obvious who or what is performing the action. Because we just established that la minoranza is the subject, there is no need to insert a word for "it" (like essa). The verb è on its own is perfectly clear.

Can rumorosa mean "vocal" or "outspoken" here, or just literally "making loud sounds"?

It can mean both! Just like in English, calling a group of people rumorosa (noisy) can mean they make a lot of literal noise, but in social or political contexts like this one, it usually means they are very vocal, outspoken, and make sure their opinions are heard.