blue bar

I do not understand the file explorer icons in Wondows 10: Why do some drives have green checkboxes others not? What does the blue bar over the drive mean? It obviously is not the same as the bar that indicates the drive filling percentage.

Can someone please help me to solve this problem. My computer freezes regularly for approximately 20 minutes each time because I keep getting a sound icon with a blue bar across the middle of my screen. My computer is brand new. There is no specific pattern to when it pops up. It is completely...