What is the definition and function of a heat break?

The heat break acts as a demarcation between the hot and cold zones of the extruder. As the hot zone melts the filament, the cold zone maintains its solidity for it to be fed smoothly into the extruder gears.

How to resolve or tackle heat creep occurrence?

Additional step for addressing heat creep includes injecting thermal grease between the heat sink and heat break, or incorporating active cooling (from a fan) towards the heat break.