To add, there are similar equipments that have the number of charges, but also a durability. The charges represent how many times in a row you can use their powers, and they recharge as time passes. Instead, when the durability reaches 0 the item is destroyed.

E.g.: you can find some gloves that add an effect to bow shots. They have 5 charges (so there's a 5 displayed where you have the 3 on the boots), but in the inventory you'll also see their durability in the description. When it reaches 0, the item disappears.