What does the circle with dots mean?
It's either Floating Toolbox (Floating Launcher)  which is a shortcut application or the Samsung Galaxy S5/S6 Toolbox. These
Floating Toolbox apps gives you access to your apps from anywhere by pressing the Floating button.

Here is a link to the Floating toolbox app: 

https://play.google.com/store/apps/details?id=com.toolbox.shortcuts

You should be able to disable / uninstall them from settings -> application manager.