Electric potential-significance

potentiality means strength, so electric potential means it tells about electric field strength.
Earth is a huge reservoir of charges and hence adding or removing of charges from the earth, there is no change occurs in its potential.
Now let us consider a positively charged body to be connected to the earth by a conducting wire, then it has less number of electrons than usually required. Hence, there is flow of electrons from the earth to the positively charged body. Therefore, conventional current flows from the body to the earth.
Now let us consider a negatively charged body to be connected to the earth by a conducting wire, then it has excessive electrons than usually required. Hence, there is flow of electrons from the body to the earth. Therefore, conventional current flows from the earth to the negatively charged body.
From above two cases, whenever the body gets its required charges, then it becomes neutral charged, i.e., there is no flow of electrons to outside or inside.
So, we say that electrical potential is physical quantity which tells about the field strength i.e., either positive charged or negative charged.