Learn Hardcore French: Paul prend son goûter dans le jardin.

In this sentence, prendre literally means "to take," but it is used idiomatically to express that Paul is having his snack. Rather than implying that he is physically taking something from someone else, it means he is consuming his snack.

Why is the possessive adjective son used here instead of sa? How do we decide which one to use?

The choice of son is determined by the gender of the noun that follows. Since goûter is a masculine noun, son is used regardless of the gender of the owner. In French, the possessive agrees with the noun it modifies, not necessarily with the subject.

What exactly does goûter mean in this sentence? Can it be translated directly as "snack" in English?

Yes, in this context goûter refers to a snack, more specifically a mid-afternoon snack that is traditional in French culture. Although goûter can also function as a verb meaning "to taste" in other contexts, here it is clearly a noun referring to the snack itself.

Why is the prepositional phrase dans le jardin used? Could it also be expressed as au jardin?

The phrase dans le jardin indicates that the snack is being taken within the boundaries of the garden. While au jardin (a contraction of à le jardin) is also used to indicate location, dans le jardin emphasizes being inside the garden space. Both expressions are acceptable, but the nuance might differ slightly depending on the context.

Is there any difference in meaning between saying Paul prend son goûter and Paul mange son goûter?

While both sentences convey that Paul is consuming his snack, the expression prendre son goûter is a common, idiomatic way in French to refer to having a snack or light meal. In contrast, manger son goûter emphasizes the act of eating. The idiomatic choice enhances the naturalness of the sentence in everyday French.