Conduction is what makes the handle of a pot hot when only the bottom of the pot is touching the stove. The heat from the burner starts the molecules in contact with the burner start to move. Those molecules bump against others in the pot, which bump others, until all the molecules in the pot, including in the handle, are moving. When someone touches the pot handle, they feel the heat. The heat has moved from the burner to the cook's hand through conduction.
Conduction is an important way that heat travels in space, but only within a spacecraft.
Since there is very little matter in deep space, heat cannot leave a spacecraft by conduction. Convection is a very important way that heat moves on Earth, but is not very important in space. Convection happens when a substance that can flow, like water or air is heated in the presence of gravity. When air or water is in the presence of gravity, the gravity pulls all of it down. The bottom of the air or water becomes denser because it is pulled down and also pushed down by the weight of the molecules on top of it.