Stats determine the advantages and weaknesses of your exosuit. The higher level and rank you are, you tend to get exosuits that have better stats.
As you level up, you will be able to buy more Exosuits. There are requirements such as level 10, level 20 and level 30. You have to buy the Exosuits using Credits that you earn along with XP after each battle.
This stat determines how many hits your suit can take before crashing. The head or helmet of the exosuit takes more damage.
This stat determines the regeneration rate for both shield energy and fuel.
This stat determines how fast your suit moves and how far it rolls and air dashes.
This stat determines the amount of fuel for your suit.
This stat determines how fast you pickup heavy weapons and boosts. This can make battles easier but still have them as a challenge.
When you select and exosuit it has a little sentance at the top describing the strong and weak points of the suit in a single sentance, but it still helps to look at the stats themselves.
Each suit makes a modification to the four heavy weapons or the Bulldog. Each suit gets one mod that can't be turned off. Each mod is usually a reference to the characters powers or something from the show. The mod changes something about the weapon to make it more combat ready. It can make the weapon better but doesn't mean you should use it as a main weapon. Sometimes certain mods lower one of the weapon's attributes but extremely raises others.