The heat supplied to the object material changes the kinetic energy of the molecules and particles in it. The molecules get separated to more distance. the bonds between them become weaker. The molecules if they seprate for then solid becomes liquid and liquid can become gas or vapor.
Size or volume becomes larger. material expands and changes shape to some extent. If volume is forced to be same then high pressure builds up in the material.
Also the way light is reflected, refracted or sound is reflected, refracted changes when the material is heated. the color of the material could change. Some materials could emit electromagentic radiation, light or sound energy.
THe object is a t a higher thermal energy than ealier. It has a potential to transfer energy to another material in contact with it.