Guides for arranging things on a slide in PowerPoint
You can align multiple objects for a clean, professional look.
When you're moving things around, smart guides appear to aid you in aligning and spacing them. Helpful Align options, and static Guides and Gridlines, are also available.
Align objects
Select the objects. Press Shift to select multiple objects.
Select Format > Align and select type of alignment:
Align Left, Align Center, or Align Right
Align Top, Align Middle, or Align Bottom
Distribute Horizontally or Distribute Vertically
Use static Guides and Gridlines
Select View > Guides to show the horizontal and vertical center lines.
Select View > Gridlines to show more gridlines.
Use the lines to align objects.
Clear Gridlines and Guides to turn them off.
Source: Microsoft