The standard Monopoly board game charges a $50 fine to leave Jail by paying.
A player sent to Jail can generally leave by paying this amount before rolling, by using a Get Out of Jail Free card, or by attempting to roll doubles. The payment is made to the Bank, not to another player. If the player remains in Jail and fails to roll doubles, the official rules limit the stay to three turns.
Jail is both a corner space and a major feature of Monopoly strategy. Landing on the Jail corner normally means being “Just Visiting,” while landing on or being sent to the Go to Jail space triggers the restriction.
Some families use house rules that change the fine or allow special deals, but the classic official amount is $50. It is not the same as a property rent, tax payment, or the $200 salary for passing GO.