overwatch
One has a forward loop with a thunderbolt in the middle, and the other has pages stacked against each other.
Sometimes one or the other flash, sometimes they both flash, and sometimes they flash rapidly or just don't flash very often.
They always appear in the upper left of the hero select screen.
What are these symbols and what do they do?
According to the Overwatch Gamepedia page:
If two Charging Reinhardts collide, both Reinhardts will be stunned and their Charges will be cancelled.
That's an unused indicator of your MMR rank for an upcoming patch that will add a Competitive mode.
In Closed Beta, there was competitive matchmaking and as such that image you posted is the default image displayed on the Competitive Play screen.
Note that currently Overwatch does not have a competitive matchmaking system; this answer will be updated appropriately when it is added.
You can see the same format in this gif Blizzard provided showcasing what competitive ranking will look like.
Best Answer
According to What the connection symbols mean,