While affixed in the gauntlet you can spend any number of charges stored within the stone to restore spells slot equal in level to the number of charges spent, this counts as a Bonus Action in combat.
(EX: Spending (6) charges within the stone can restore (1) level six spell slot, (2) level three slots, (3) level two slots, (6) level one slots, or any combination not exceeding a total of (6))

 

While affixed into the gauntlet you can use the Time Stone to target an object and manipulate the flow of time around that object. By spending (2) charges you can accelerate or reverse the flow of time around the object up to a year into the future or the past. The effect cannot target living creatures and cannot restore corpses back to life, but it can accelerate or reverse the decomposition process. While in combat this counts as an Action.

(EX: By targeting an iron key that was broken a few months ago you can reverse the flow of time around the key until the broken pieces rejoin, similarly you can place the same key in a bowl of water and accelerate the flow of time until the key becomes terribly rusted and unusable.)      

 

The Time stone has (9) charges stored within it, charges return after a long rest and the stone can hold no more than (9).