Why does last row and columns being True means that the subset equals each other?

" From the above visualization, we can clearly see that it is possible to partition the given set into two subsets with equal sums, as shown by bottom-right cell: dp[3][5] => T"

I get how they come up with the True in the cell. I just don’t understand why the last cell being true means that you can partition the half sum into two subset?