The schematic doesn't make sense so there must be errors in it I'm afraid.
It looks to be a low power headlight, maybe 3W at most so it can't be very bright. Even if both high and low beams are on together it probably doesn't exceed 6W. Trying to best guess at what it does, the small LEDs are on all the time, the big LEDs are either on full brightness for HB or chopped by the IC for LB so they drop in brightness. The values in the schematic do not make any sense though and the current flow through the LEDs is unclear.
Brian.