Aligning objects with the T-squares
Use the T-squares — movable horizontal and vertical guide lines — to help you align objects in Layout mode. An object's left or right boundary, top or bottom boundary, or center “snaps” to the T-square lines as you drag the object.
 
Choose View menu > T-Squares. To hide it, choose T-Squares again.
Using the Selection tool Selection tool, move either the horizontal or vertical T-square line.
Press Alt (Windows) or Command (Mac OS) as you drag an object.
Related topics 
Selecting and working with objects on a layout
Aligning or distributing objects