What is propositional/first-order logic?
If you have ever done math or programmed a computer, then you have already used propositional logic (PL). It’s an artificial language (or formal system) used to describe a limited world. It has constants, variables, functions, relations, etc. It’s very simple. The R&N textbook cacn introduce you to both (ch. 7-8). If you want another physical reference, check out Language, Proof, and Logic; they have it at the library and the bookstore.
