Quid pro quo is a Latin term meaning "something for something". It is often referred to in the context of contracts, since it stands for the contractual concept of consideration, which is the value received for a promise to do or not do something. The contractual term for quid pro quo is "mutual consideration".
In order for a contract to be enforceable, it must involved the exchange of things of value. The things exchanged may be goods or services. A person entering a contract for services may fulfill the quid pro quo aspect of the bargain by offering the party performing the services other goods, money or services in return.