Question

What does one mean by exothermic and endothermic

Answer 1

Exothermic are those reactions in which energy is released in form of heat.
Endothermic are those reactions in which energy is absorbed in form of heat.
First attachment is example for exothermic, and the second for endothermic.

Answer 2

If energy  needed in bond breaking is less than energy released when forming new bonds .The chemical reaction is of exothermic nature.The container becomes hot.
If energy needed in bond breaking is more than energy released in bond making ,the chemical reaction is of endothermic nature.The container becomes cold.

Hope it helps u ....