You can make text appear one line at a time on your slide.
On the slide, select the box that contains your text.
On the Animations tab, pick an animation, such as Appear, Fade In, or Fly In.
For some animations, such as Fly In, click Effects Options, as you’ll need to pick a direction for the bullets to fly in from, such as bottom, top, left, or right.
Click Effect Options, and then click By Paragraph to make the paragraphs of text appear one at a time.
The desktop versions of PowerPoint immediately preview the animation for you. To preview the animation in PowerPoint Online, in the lower-right corner of the task bar, click Slide Show View, and then click to see each paragraph of text appear one at a time.
By default, when you present in Slide Show, each paragraph appears in response to a click. That way, you control when each paragraph appears.
In the desktop versions of PowerPoint, you can modify this setting by using the Start, Duration, and Delay controls on the far right end of the Animation tab of the ribbon.
For more about animating slide content, see: