When you create a character you will choose a selection of items to add to their playbook. You may also have the opportunity to add new items to this list of equipment as you explore and perform downtime activities. Equipment is primarily used to perform actions; you cannot, for example, strike a target at range without a projectile weapon. It can also be spent to help prevent complications from a failure.
You may use an unspent item to perform any number of actions. If it requires consumable objects, such as ammunition or hardware, you either have enough on you or can find replacements easily enough to keep it functional. You cannot use equipment to perform actions once it has become SPENT.
You may choose to SPEND an item when an action’s complications have been declared, but before their mechanical effects have been applied. You do not have to have been performing the action which caused the complication. You may choose to spend any piece of equipment you have, not necessarily the one you were using for the action. When you do, mark that the item is spent and narrate how you are using that item to prevent the stated complication.
You may also spend an item to improve the position of an unsafe action. When the dealer declares your action to be unsafe, you may declare you are spending an item and declare how it is helping you make the action safe. You may spend the item you are using to perform the action, after which it will be spent and unable to allow you to perform further actions with it.