What kind of sentence is this john spent the afternoon reading and eating pretzels?

The sentence "John spent the afternoon reading and eating pretzels" is a compound sentence.

A compound sentence contains two independent clauses, which are two grammatically complete sentences that are joined by a conjunction such as "and", "but", "or", "nor", "so", "for", etc.

This sentence consists of two independent clauses: "John spent the afternoon reading" and "John spent the afternoon eating pretzels".