Stretch command have S shortcut. It is one of helpful command in AutoCAD. You can use this command to modify length or move an object. You should note selection way when perform this command. If you modify length, you can use Window. If you want to move object, you can use Cross Window.
What is Window selection?
You can define a window selection by clicking at two points. Click first point on the left side, and 2nd point on the right side. This will select all elements inside the window.
What is Cross Window selection?
Basically if your window selection defined from right to left, then it will be cross window selection. It will select all elements inside and touching the window.
How to use Stretch command?
Command: S > enter
Select object: window or cross window > enter
Specify base point or [Displacement] <displacement>: click on one point
Specify second point or [use first point as displacement] : click on second point or input value
You can practice with video tutorial below: