After you destroy a breakable item, it will hold a certain amount of resources (it is possible to have multiple types of resources inside one breakable item)

As you are destroying it - the resources will fly up and animate going into your resource wallet - inventory.

Every time you gain at least one resource, the wallet will be visible on the top right part of the screen for a short amount of time.

If you are unsure how many resources you have - needing them to repair an item, or in order to cast a spell - the UI window will always tell you how many of a specific resource you need.
If you don't have enough resources to do something - it will be clearly communicated in the UI window - the number required will be either red , or show you exactly how many are you still missing.

A green number means you have enough of the required resource.

If you don't have enough resources, you can always get the missing amount by exchanging the special currency Gems for the resource you are missing, or harvest them from different objects.