What is this called?

Solution 1:

Those are your "Field Upgrades" you can unlock and earn many different upgrades which you can switch out like a kit. Each one has 4 levels of perks that they give. Each bar is a new perk. As you fill up your bar, you unlock more perks. You'll see in that screenshot they have unlocked 1 of 4 of their perks currently.

1. You get points towards these perks by doing SQUAD actions. Squad orders, squad heal, squad revive ect...
2. Your perks that you get are based on kit you chose with that class.
3. Your perks will be set back one level every time you entire squad gets wiped.
4. Unlike squad perks from BF3, these only apply to your personal player.

Your best bet is to choose perks that align with your play style and stick to your squad. By getting squad points you unlock them all pretty fast in a game. Also you should always have (preferably your squad leader) in the back where they likely will not be killed. Your squad leader should also make sure they are issuing orders on points to get tons of bonus points.

The possible Field Upgrades are:

All taken from here where you can also get more information!