The suit selection widget allows you to select or deselect suit symbols. Per default you can select suits with the left mouse button and unselect them with the right mouse button.
Below the 4x4 matrix of suits, there are also buttons to select either all suits, no suits, only diamonds, only hearts, only spades, or only clubs.
Having a specific selection will affect which suits are selected, when you click on the hand range matrix. For example, if you only select hearts:
, then clicking on AA,AKo,AKs in the matrix selects:
AA: AdAh, AhAs, AhAc
While in PokerRanger1 it was necessary to use suits for weighting hands, there is another mechanism to weight ranges in PokerRanger2 which is easier, more intuitive, and works with other Poker tools like PIOSolver. Learn more about weighting ranges.
By the way, the abover screenshot appears if you hover AK.