Super admins can create sandbox accounts to test functionalities without impacting your main account. For example, connect an app app to your sandbox account to test a new integration. You can sync data from your main account to test the integration
If you add users to your sandbox account, HubSpot will not create them as new users in your main account. For example, if you add a consultant or contract worker to a sandbox, they will not have access to your main account. Only super admins are added by default as users in a sandbox account.
Similarly, paid seats assigned in a sandbox account will not impact the seats in your main account. Users with a paid Sales Hub or Service Hub seat in your main account will also not automatically be assigned that seat if they are added to the sandbox account.