Explanation of formula

There is a clever piece of conditional formatting designed to show if a formula has been overwritten. It works by creating a range called (say) CellHasFormula and then entering =GET.CELLl(48,Indirect("rc",false)) in the reference box. In the cell you wish to conditionally format you enter =CellHasFormula. If the formula in that cell is overwritten, then the conditional formatting is displayed.

Can someone explain to me how it works?

Thanks