Abstract Datasheet Dimension Notation
P is the nominal pitch of 1.27mm (0.05"). There are 4 spaces for 5 pads so the total distance between centers of the outer pads in the group is 5.08mm (0.2").

The other notation indicates that there are 10 pads, each 0.7mm wide and 4 pads, each 0.8mm wide. It is obvious in this case which are which, but in general when you see this kind of notation with a quantity in a mechanical drawing look for symmetry.