Final answer:
To insert a new line in an Excel cell on a Mac, use the control + option + enter key combination.
Step-by-step explanation:
To insert a new line in an Excel cell on a Mac, you can use the control + option + enter key combination. Here are the steps:
Select the cell where you want to insert a new line.
Hold down the control and option keys on your keyboard.
Press the enter key.
By using this key combination, you can easily add a new line within a single cell in Excel on a Mac.