How do armor works?

I don’t know how it works.

Armor, in a simple nutshell, decreases the amount of damage the hero receives on their base health, so if a hero such as Vanguard gains a ton of armor, he will increase his survivability.

This old conversation might have something of use if you’re looking for more details:

To add and simplify, if a hero has 100 armour and an enemy has 120 attack then the hero only receives 20 damage. It obviously gets a bit more complicated with elements and mods etc but that’s the base of it. It boils down to basic addition and subtraction, some heroes are more tanky than others so can take more damage such as Klayton.

The amount of armor they have reduces the base weapon damage a hero has, for example a hero shoots for 20k and a cast has 13k armor, she deals 7k

What is your ign maybe i can help

So if 1 have 100 armor, other with less than 101 dmg won’t affect him? And doesn’t that mean single bullet type heroes will have more advantages than heroes that fire multiple bullet at once?

No, it gets a bit complicated because every hero does both elemental and kinetic damage. So you see red numbers mean the defence has reduced your attack by a certain amount of Elemental damage when using against the wrong hero type. When kinetic and elemental damage is combined you get your overall dps of a hero so damage will always be done