Overview of formulas in Excel – Microsoft Support

To see a formula, select a cell, and it will appear in the formula bar. Enter a formula that contains a built-in function Select an empty cell. Type an equal sign = and then type a function. For example, =SUM for getting the total sales. Type an opening parenthesis (. Select the range of cells, and then type a closing parenthesis).

https://support.microsoft.com/en-us/office/overview-of-formulas-in-excel-ecfdc708-9162-49e8-b993-c311f47ca173