what is this thing on the text frame

[aerin_3751]

I keep instinctively trying to resize my text frames using these......boxes? handles? and clicking on the left OR right one like....sucks my text out and makes a small picture/icon of my text and makes it copy/pasteable. What is this thing even called and how do I make it not do that? I just want to be able to shorten or lengthen text frames without changing their other dimension quickly and easily. 

[Joel Cherney]

Your frame is so small that your out port and your handle are in the same place. The in port and out port are for threading frames together into a single story. Here's a quick GIF with a rather taller text frame so you can see an example of how the in port and out port are used:

When your frame is small, InDesign maps the functionality of the side handles to the in port and out port. So if you click and drag, it should behave like a handle, but if you click and release without moving the mouse it should behave like a port. 

[Brad @ Roaring Mouse · Accepted solution]

The bigger boxes, top left and bottom right, are the In/Out Ports for linking text. When your text box gets too small, these will overlap the sizing boxes underneath. When that happens, just hold your mouse button down for a moment and the arrows will appear allowing you to resize the box.