The FM repeater receives one signal at a time and simultaneousy rebroadcatsts it on another frequency using many more watts of power than available from a small had-held radio. The whole country has these repeaters. You can listen to one on a radio scanner. When a ham is traveling he or she can find a repeater to use. One can carry on a nice static-free FM radio conversation via a radio that fits in the shirt pocket or in a purse.
Linked repeaters allow fun, wireless communication across an entire state.
Repeaters use common transmit and receive frequency pairs. The frequency pairs in use are informally assigned by groups of hams so that any Frequency pair in use is far enough from another repeater so as not to cause unwanted interference. Amateur radio satellites are a cutting-edge use of technology in amateur radio. Radio amateurs use their hand-held radio to communicate through an amateur radio satellite, when the satellite is overhead. If you ask different hams you would get many different answers.