One very interesting phenomenon happens when we approach a charged object to a neutral object. Regardless of the charged object’s sign, it exerts an attractive force on the neutral object. We can explain this behavior through a concept called charge polarization. Charge polarization happens when there is a separation of positive and negative charges within a neutral object.
When we approach a positively charged rod towards a neutral metal, the metal is polarized, with the negative charges closer to the rod while the positive charges go farther away. The metal’s net charge is still zero, but it has been polarized. As the metal is polarized, there is a polarization force between the metal and the rod, which attracts them even though the metal is not charged.

Note: The polarization force is always an attractive force.