Page "Free agent" Paragraph 3

The specific rules of restricted free agency vary among the major professional sports, but in principle it means that a player is free to solicit offers from other teams for new contracts.

However, before this player is allowed to sign with the new club, the current club has a chance to match ( or come within 10 % in some leagues ) the terms of the new contract in which case the player must remain with the original team.

In some leagues, if the original team decides not to match the other team's offer for the restricted free agent, the new team provides some number of draft selections to the original team as compensation for losing the player.