The Grid tab is the second tab in the PIMS LS ribbon.
Here you will find tools to create grids of images i.e. view more than one image at a time. It's a very flexible system, allowing you to view anywhere from 2 to 36 images similtaneously - provided your screen is big enough!
There are dedicated sub articles on the Size, Synchronize and Slide tool groups.
The other sections are: