Learn Italian: Serve autodisciplina: chi ama viaggiare, chi vuole stabilizzarsi. - Self-discipline is needed: some love traveling, some want to settle down.

The distributive correlative chi ... chi ... is used to contrast different groups, much like "some ... some ..." in English. However, because chi (who) is a singular pronoun in Italian, any verb that follows it must always take the third-person singular form. So, you must say chi ama and chi vuole, even when talking about multiple people.

I learned that servire means "to serve". How does Serve autodisciplina mean "Self-discipline is needed"?

Besides "to serve", servire is very frequently used to mean "to be needed" or "to be necessary". When used this way, the thing that is needed is actually the grammatical subject of the sentence. Here, autodisciplina is the subject doing the "being necessary", which is why the verb serve is conjugated in the third-person singular.

Why is there a -si attached to the end of stabilizzarsi?

The base verb is stabilizzare, which means "to stabilize" (to make something else stable). Adding the reflexive pronoun -si makes it stabilizzarsi, shifting the focus back to the subject: "to stabilize oneself" or "to settle down". Because it follows the modal verb vuole (wants), the verb stays in its infinitive form, and the pronoun -si attaches directly to the end after dropping the final "e".