STR represents Strength

DEF represents defense 

DEX for quickness/reflexes

AGI - Agility

HP - health points / lifeforce 

For Ex: HP - S will have huge lifeforce like dragons which is like 1000 years 

& HP also represents their health status 

For Ex: if HP : F- ,is very weak in constitution and have low lifeforce is likely to die faster

For Humans Rank E is standard 

Different Races have different HP 

Representing their lifeforces 

HP also represents their Constitution

Ranks for Stats

F-

F

F+

E-

E

E+

D-

D

D+

C- & so on 

Ranks for skills

From D to S

EX - Exclusive 

Most people have at most 3 passive skills and 

Active skills can be increased by any number