Suppose we want to positively charge a metal rod A. Place it on an insulating stand and touch it with a positively charged glass rod B. The rod A gets positively charged.
Explanation in terms of movement of electrons — The glass rod B is positively charged so it has a deficiency of electrons. When it is touched with the metal rod A, the free electrons of the rod A move to the glass rod B. Due to loss of electrons in the rod A, it becomes positively charged.