Conduction is heat transferred through molecular collisions from a hot object to a colder one. One molecule transfers energy by "bumping" into another, which in turn collides with another and so on, and heat is transferred through materials. In such collisions the faster atoms lose some speed and the slower ones gain speed; thus, the fast ones transfer some of their energy to the slow ones.
Materials which have a high thermal conductivity have, by definition, a low thermal resistance (or R value- they are poor heat insulators. On the other hand, materials with a low thermal conductivity have a high thermal resistance - they are good heat insulators.