Disinfection
Disinfection is using a cleaning product to kill germs on a surface.
Think of it this way
Bleach on a cutting board works the same way as disinfection. The board has tiny germs sitting on its surface like dirt specks. You pour a few drops of bleach onto the surface. The bleach spreads across the board and breaks apart the germs until they stop working.
Explaining disinfection by grade level
Think about wiping a door handle with a cleaning wipe. The door handle looks clean, but tiny germs live on it. The wipe has a germ killer mixed in. It soaks into the germs and stops them from growing.