The Flip button will flip the selected objects over horizontally or vertically. This is similar to Mirror, except this actually moves the object instead of making a copy of it. 

Select the desired object(s).

Select the desired direction from the Flip button dropdown control.

Click the Flip button.

Here we selected to Flip the object horizontally.

Here we selected to Flip the design Vertically.

Here we selected to Flip the design Horizontally, then we selected to Flip it Vertically.

Use Edit > Flip Design > Horizontal/Vertical to flip the entire design horizontally or vertically.

The entire design is flipped in the direction selected.

Optionally, use the Mirror button to make a mirror copy of the selected objects. 

This will allow you to manually select the desired objects that will be mirrored along the axis line.