In Excel, you can use relative or absolute references for both columns and rows. $A1 refers absolutely to column A, A$1 refers absolutely to row 1, $A$1 refers absolutely to cell A1, etc.

When you copy the cell/range, using copy-paste, copy-paste special>formulas, or dragging e.g. down or to right from lower rihgt edge of cell/range, absolute references don't change, but relative references do change.
P.e. when in cell X3 you have a formula =SUM($E3:$F3)-SUM($C3,$G3), and you copy the this to cell X4, the formula in X4 will be =SUM($E4:$F4)-SUM($C4,$G4). When you copy X3 to Z3, the formula in C3 will be =SUM($E3:$F3)-SUM($C3,$G3) - the formula doesn't change, as the row is same, and column references are absolute.