how I can check the file capacity or data usage (in GB) of my account?

I'd be happy to assist you with checking your account's data, @va-alliza-polecios.

You can find the information in the Accounts and Settings section. Here’s how to do it:

1. Navigate the Gear icon.
2. Click the Accounts and settings under the Your Company section.
3. Select Usage. 
    

From there, you’ll be able to see how much of your account limits you've utilized for the number of accounts in your Chart of accounts, the number of classes and locations (if your plan includes these features), the number of users, as well as other limits associated with your subscription plan.

The Community remains open for any additional QBO questions you may have. We’re always here to assist you!