What is lone pair and also plz find lone pair of NH3

Dear Student
A lone pair is a valence pair of electrons which are not formed by bonding or sharing by other atoms or molecules. As they are valence electrons, they are found in the outermost shell of the atom.

Examples :

In Ammonia,
Nitrogen has the configuration 1s² 2s² 2p³ . So, It has 3 unpaired electrons in the 3 orbitals of p-sub shell but the 2s orbital has a pair of electrons which is the lone pair of electrons.

Regards