The ROW function in Excel is a worksheet function that returns the row number of a cell reference. It takes a cell reference as its argument and returns the row number of that cell.

Syntax
=ROW([reference])

[reference] - reference for which you want to return the row number. 

Here are a few examples of using the ROW function:
1. =ROW(A1) - returns the row number of cell A1.
2. =ROW() - returns the row number of the cell in which the formula is used.
3. =ROW(C5:D10) - returns the starting row number of the range C5:D10.