There are five modes: Heat, Cool, Heat & Cool, Dry, Fan Only
Heat: The unit actively heats when the indoor temperature is below the heating setpoint.
Cool: The unit actively cools when the indoor temperature is above the cooling setpoint.
Heat & Cool: The unit heats when the indoor temperature is below the heating setpoint and cools when it is above the cooling setpoint.
Dry: The unit can create a drier environment.
Fan Only: Only the indoor fan runs continuously until the unit is turned off or the operation mode is changed.