Franchise coins or gold can be used to obtain a franchise player who will play for your team for 5 games.  When you have an active franchise player, you can extend his amount of games another 5 games by either using a franchise coin, or by using gold if you do not have any franchise coins remaining.

You can spend gold to unlock additional franchise slots, which allow you to use coins or gold to fill with a franchise player. You can have a total of 5 active franchise players at any given time if you unlock and fill every slot.

Please note that in order to use franchise players you must have your Roster Decisions set to "Potential" instead of "Current".

Please also note that a franchise player will not be able to be used if your current roster is higher powered.