Learn Italian: Dobbiamo trovare una discoteca che metta buona musica. - We have to find a nightclub that plays good music.

We use the subjunctive metta because we haven't found the nightclub yet; it is just a desired place with a specific quality. When a relative clause (starting with che) describes something you are looking for but aren't sure exists yet, Italian requires the subjunctive. If you were talking about a specific club you already knew, you would use the indicative: Conosco una discoteca che mette buona musica (I know a club that plays good music).

Why do we use mettere (to put) to mean "plays" music?

In Italian, mettere is the standard verb for playing recorded music, records, or playlists. Think of it as a DJ "putting on" a track. You will often hear mettere musica used in the context of parties, clubs, or the radio. Remember that giocare is only for playing games or sports, and suonare is mostly used for playing a musical instrument.

Could I say musica buona instead of buona musica?

You could, but buona musica sounds much more natural here. Very common descriptive adjectives like buono (good), bello (beautiful), and bravo (good/skilled) usually go before the noun to express a general, subjective quality. Putting it after the noun (musica buona) can sound a bit clunky or like you are specifically emphasizing its contrast to bad music.

Why doesn't trovare need a preposition before it, like or ?