On an NFL football team, there are generally around fifty-five (55) total players on the active roster. However, only 46 of them dress for the game, which means 46 players are ready to go in when needed.
However, during a game, there are a lot less players on the field- only 11. Each of the 11 positions on the field also require backups, with a few bench players serving as backups for multiple positions for depth at more important positions, such as wide receiver or running back.
6 players are permitted to be on the inactive list. The inactive players list is the area between active players and the injured reserve list-which is a list of injured players that aren't extremely injured enough to be put on the injured reserve list. The inactive players list ensures that each team has an equal balance of healthy and active players so there is no unfair advantage.