Simple Definition:

Conduction is the process by which heat or electricity moves through a material or substance [the stuff that something is made of]. When an object is heated, the heat energy is transferred through the material by the movement of the particles [tiny pieces such as atoms, that make up that thing]. The particles in the material collide with each other, transferring energy from one particle to the next. Examples of conduction include heating a metal spoon in a cup of hot soup and feeling the heat travel up the spoon’s handle.

Very Simple Definition:

Conduction is when heat or electricity flows through a material (like metal or water) that is touching another hot or charged material. For example, when you hold a metal spoon that has been in hot soup, the heat from the spoon is transferred to your hand through conduction.