A more thorough explanation:

Definition: A limitation or restriction.

Example: A right to take fish from a canal without stint can exist as a profit in gross.

This means that there may be a limit to the number of fish that can be caught from a canal or a restriction on the time when fishing is allowed.

Definition: A salary or other regular, periodic payment.

Example: The company provides a stipend to its interns.

This means that the interns receive a regular payment for their work, usually on a monthly or bi-weekly basis.

Definition: An oral contract requiring a formal question and reply, binding the replier to do what was asked.

Example: Spondesne mihi decem aureos dare (do you engage to give me ten aurei, or gold-pieces): answer, Spondeo (I engage).

This means that a person makes a promise in response to a question asked by another person, and this promise is legally binding. No consideration is required, which means that no payment or exchange is necessary for the contract to be valid.