Select the cell(s) or range you want to wrap
Go to the Home tab
In the Alignment group, click Wrap Text
If needed, resize the row height to display wrapped lines:
Select the row(s)
Go to Home > Format > AutoFit Row Height
To apply wrapping to specific text only:
Double-click the cell and place the cursor where you want the break
Press Alt + Enter to insert a line break
To turn off wrapping:
Select the cell(s)
Go to Home > Alignment > click Wrap Text again