Yes. It’s a standard part of most employment contracts, but not so heard of in football so its term of the week at the minute.
The term originated in the British civil service where employees had the right to request special leave for exceptional purposes. "Gardening leave" became a euphemism for "suspended" as an employee who was formally suspended pending an investigation into their conduct would often request to be out of the office on special leave instead. The term came to widespread public attention in 1986 when it was used in the BBC sitcom “Yes, Prime Minister” episode "One of Us"