At the top of the back office is a bar containing a handful of information and links:
The PrestaShop logo.
Quick Access: the menu groups together shortcuts to the most useful pages, for example Orders, New voucher, New product, and New category, which you can set by clicking on "Manage quick accesses".
A search field. Search the whole back office for information or a feature.
The name of your shop. Clicking on this link takes you directly to your shop's Front Office.
Notification icon (small bell). This symbol will have a number by it depending on whether you have any new orders, new customers or new messages, as you can see in the image below.
The person icon in the top right. This menu will give you access to two options, first the "My preferences" link which will open the preferences page for your current user account, where you can change certain options like the back office language or your password, and the "Sign out" link which will sign you out of the account currently in use.