The Underline feature in PowerPoint allows users to draw a line under their text. Follow the steps to use the Underline feature in PowerPoint:
On the Home tab, click the underline button. If you wish to add a different style of underlining, click the More button in the Font group.
A Font dialog box will open. On the Font tab, in the Underline section, choose a style from the list. You can also choose a color for the line and then click OK.