These labels indicate the type of equipment a thermostat will be able to control. For example, a "2 Heat/ 2 Cool" thermostat is capable of controlling up to two stages of heating and 2 stages of cooling. This is the maximum number of stages the thermostat will control, so it would work in a system with a two stage furnace and a single stage air conditioner just as well as in a system with only a single stage furnace and no cooling system at all. This is useful as some thermostats offering features like internet or mobile control are generally capable to handling multiple stages of heating and cooling. Be aware that sometimes the same thermostat will control different numbers of stages depending on whether it is used in a system with or without a heat pump.