How is thermal energy transferred?

Thermal energy can be transferred in a few ways but friction is a good example, other ways include, radiation, convection, or conduction.

Heat may be transferred by means of conduction, convection, or radiation. Conduction is the transfer of thermal energy (heat in transfer) due to collisions between the molecules in the object. Collisions between adjacent atoms and molecules transfer kinetic energy from the warmer to the cooler object.