Have you ever had someone rub a balloon against your hair? What happened? Did your hair stand up? Did the balloon then stick to the wall? How did that happen? All matter -- every object, you, even the air -- has tiny bits of electricity called electric charges.
Every atom of matter has electrons having electric charges. When you rub two objects together, you can cause these charges to move from one object to another. The balloon picked up charges from your hair. The balloon and the wall have charges that are unlike (or opposite from) each other. Unlike charges attract or pull toward each other. This pulling force between unlike charges makes the balloon stick to the wall.
Try rubbing two balloons with a piece of wool. If you hold the two balloons near each other, they will push away from each other. The balloons will have electric charges that are the same. Like charges push away from (repel) each other.