Select the cell immediately to the right of the columns you want to freeze and directly below the rows you want to keep visible
Go to the View tab
Click Freeze Panes
Select Freeze Panes from the dropdown
To freeze only columns, select the first cell in the row below the columns you want frozen
To freeze the first multiple columns and rows together, choose the cell that starts the unfrozen area
To unfreeze columns, go to View
Click Freeze Panes
Select Unfreeze Panes