What do Physical PEN, Magic PEN and Spell Vamp means in Mobile Legends: Bang Bang

Some items in Mobile Legends: Bang Bang game, has effects and unique that different each others. I don't understand what this mean :

1. Physical ATK vs. Physical PEN
2. Magic Power vs. Magic PEN
3. Spell Vamp

And also some hero has over power with true damage. What items should I use for defense against true damage?

Solution 1:

Physical ATK increases your ATK which increases Basic Attack Damage and Abilities scaling from Physical ATK

vs

Physical PEN negates the value of armor of enemies base on the quantity of penetration which makes Basic Attacks and Abilities with Physical Damage deal more damage

same goes for Magic Power and Magic PEN

While Spell Vamp gives you lifesteal depending on the damage you deal with your abilities

Solution 2:

There are three types of damages in Mobile Legends:

1. Physical Damage
2. Magical Damage
3. True Damage

Physical damage is dealt using physical attack (similarly for magical damage). Both these damages can be countered using their corresponding defenses. True damage can not be countered using any form of defense or item, but true damage can be blocked using shields.

The damage you deal to an enemy depends on his ability to counter your (PHYS/MAG) attack using his defense, but this defense can in turn be reduced using penetration. Penetration decreases the enemy unit's defense stat, so you can deal more damage.

Spell vamp gives you lifesteal on physical damage dealt using your skills. Some heroes have passives for spell vamp (Alucard, Ruby) while others can get spell vamp using items like Bloodlust Axe. Spell vamp is very useful for heroes that primarily rely on their skills to deal damage for eg. Hayabuza, Martis, Lapu-Lapu etc.