Gaining Resolve points: Each time you gain a level you gain resolve points equal to the proficiency bonus for the new level.
You can have a maximum of your level in resolve points, any excess is lost. (Thus you start play at level 1 with 1 resolve point)
Using: each of the uses costs one resolve point
Flashback: You can specify an action you did in the past. The action has to be something you could have done and has to be suitable for your character. Examples: Buy some common gear, ask a scholar in the village about some you forgot to ask, ask you neighbor to feed your cats while you are away etc.
Recover power: You can recover uses of one power equal to reovery of that power after a short rest. Only affects that one power.
Stay Up: On going to 0 hitpoints but not dying directly, you can immediately spend hitdice as after a short rest, but you have to decide how many to use before any rolls
Recover health: You can spend hitdice as after a short rest as your action for a round.
Reduce exhaustion: If used as an action, reduce exhaustion by one level. If used after a short rest, reduce exhaustion by two levels. If used after a long rest remove all levels.