The grid is every starting hand, once
The rule
Pairs run down the diagonal, suited hands sit above it, offsuit hands below. One hundred and sixty nine boxes, no repeats.
Every hand you can be dealt appears exactly once. Ace king suited is one box, ace king offsuit is another, and the grid is read from the top left, where the strongest hands are, outwards.
The boxes are not equally likely, which matters more than it looks. A pair is six combinations, a suited hand four, an offsuit hand twelve. So the offsuit half of the grid is most of the hands you are actually dealt, even though it takes up the same space as the suited half.
Read more: range, opening range, combos