Homeostasis can be defined as the regulation of the internal environment in the body so as to maintain a stable, constant condition. Things that may be regulated are temperature, amount of glucose and water content.
The normal body temperature needs to be around 37C for your enzymes to work well. Your skin has many structures that can help control your body temperature. Sweat evapourates from the surface of your skin, transferring heat energy to your surroundings and cooling you down (through latent heat of vapourisation).