Hard to tell in that screenshot, but it looks like column "S" is complete with data
Range(Range("S2"), Range("S2").End(xlDown)).Offset(0, 2) = "No"
But, let us say that Column "S" had some empty cells in it, but the last cell was not empty. Then
Range(Range("S2"), Cells(Rows.Count, "S").End(xlUp)).Offset(0, 2) = "No"
Now, let us imagine that some other column, even in another sheet or workbook, was complete with data. Say... Column "X"
Dim LastRow As Long
LastRow = Cells(Rows.Count, "X").End(xlUp).Row
Range("U2:U" & LastRow) = "No"