There are four resources your character has in GNT Special. In no particular order:
Health starts out full. It decreases whenever someone hits you with an attack, or connects with an attack that chips. If it reaches zero, you lose. Most characters have the same amount of health, with very few exceptions (ANBU Kakashi, Kankuro, Granny Chiyo, Hinata in Awakened mode). It’s the green meter at the top of the screen near your character portrait.
Chakra starts out at 50%, and then carries over from round to round. It is consumed for X moves, and occasionally some A moves on characters. It increases whenever you do damage, whenever you take damage, and a little bit just for doing some moves. It’s the equivalent of the special meter in other fighting games. It’s the blue meter at the bottom of the screen or just under your health bar.
Escape starts at 50%, and then carries over from round to round. When it is full you can perform escape teleports when someone attacks you, at the cost of the entire meter. It fills up whenever you take damage. Think of it like a second special meter only used for escaping chains. It’s the orange meter next to your health bar.
Guard starts out at 100%, and refills quickly over time when you’re not in blockstun. It is decreased whenever you block an attack, with different attacks doing different guard damage. If it reaches zero, your character suffers a ‘guard break’ – you stagger and are vulnerable to attacks, and you lose all your chakra. There isn’t an explicit meter for guard in GNT Special (Earlier games in the series did have one though). You can get a sense of what your guard is like by looking at the colour of the flash whenever you block an attack – blue means it’s okay, yellow is mediumish, red is quite low.