Top left stat is how much damage you've dealt on that life which is then carried over as health when you lose a life
Bottom left stat is the number of remaining lives you have
Bottom right stat is the current damage multiplier being applied (goes up with each life you lose)

1000 damage is the maximum so you will gain an extra 1000HP + 500HP (which is the default Mummy HP when you equip it) on next respawn with the suit