Learn Italian: Prima di uscire leggo l'oroscopo; ci credo molto. - Before going out I read the horoscope; I believe in it a lot.

The pronoun ci here replaces the phrase a + [something]. The verb credere (to believe) is followed by the preposition a when you believe in something. So, instead of repeating credo all'oroscopo (I believe in the horoscope), you use ci to mean "in it": ci credo.

Wait, doesn't "believe in" use the preposition in? Why does ci replace it?

In English, you believe in horoscopes or magic. But in Italian, the verb is usually credere a (literally "to believe to") for superstitions, concepts, or facts. Because it requires the preposition a, it works perfectly with the pronoun ci. Italian only uses credere in for things like believing in God or having deep faith in yourself.

Why is uscire in the infinitive (to go out) instead of conjugated like esco (I go out)?

In Italian, when the subject of both actions is the same (you are the one going out and the one reading), you use prima di followed by an infinitive verb. This structure is similar to saying "Before going out" in English.

Could molto change its ending here to match a noun?