Active Sessions is a section where you can see and control all the devices from which you are logged into your wallet. Each active session displays the device that was logged in, its IP address, the time it was last online, and the current status (online, logged in, offline, and so on).
You can end the session of any device from the list by clicking the X button to the right of it. In this case, it gets completely logged out of your account — in order to log in again, you need to sign in with your Google or Apple account, enter the PIN code, and go through two-factor authentication if it is enabled.