žeravica
hot coals, or just coals, is not it. "žeravica" is the red glowing pieces beneath the flame, and doesn't require any coal at all. It can be wood, or just weeds.
embers is not it, because it assumes a single piece of žeravica in the ashes of the dying fire. Žeravica is the total of such pieces also when the fire is fully aglow.