Answer:
The second law of thermodynamics describes the direction in which heat is transferred between systems, heat is a form of energy in transition.
This law says that heat or energy always flows spontaneously from the body or system with a higher temperature to a lower temperature system (from something hot to something cold, and not the other way around).
This is why if we leave an ice at room temperature it will eventually melt, because the environment transferred energy to the ice and caused its temperature to increase and thus to turn into a liquid form.
The second law can also be interpreted in terms of entropy, and tells us that entropy, which is often interpreted as a measure of disorder, always increases.