When a lead generation form is filled out and you have accepted the Pending Contact you start to track their activity on your website and Campus will notify you of this activity in the bottom right hand corner of your screen.
These real time pop ups are a great way to see how contacts are interacting with you but might end up slightly distracting when you're working in other Campus modules.
To turn these off go to your Account module (by clicking on the Account item in the dropdown menu underneath the user picture top right of your screen). Then select the Notifications item in the submenu.
Now simply toggle the feature on or off using the checkbox. N.B. This option can be varied from user to user.