In opprison, there are 2 types of beacons :
1. The beacons which are shown in the scoreboard on right side of the screen. These are the ones which are used for prestige. Whenever you want to /prestige, You would need a certain amount of money as well as beacons to prestige.
2. The physical beacons which you get when you mine a beacon block in mines. The only use of this is placing in your cell if you want to otherwise you can just /trash them.