The outermost (valance) electron's effective nuclear charge is specified as its charge.
In addition, the electron or multi-electron considers the number of sheltering electrons that circle the nucleus.
The screening or shielding effect:
When the number of inner electrons is greater, they shelter the outermost electron from the nucleus, allowing it to neglect the nuclear pull to some extent.
This is referred to as the shielding or screening effect.
The electrons in the valence shell are pulled to the nucleus in a multielectron atom, and these electrons are repulsed by the electrons in the inner shells.
As a result of the repulsive forces acting in opposite directions, the actual force of attraction between the nucleus and the valence electrons is slightly reduced.
The screening effect or shielding effect refers to the decrease in the nucleus's force of attraction on valence electrons due to the existence of electrons in the inner shells.