Using our knowledge of conductance, we can deduce the Electrical Potential difference (the voltage) of capacitors in a circuit
We know that electrical potential between two points is the work done against an electric field to move a positive test charge between those points.
A battery has voltage due to a difference of charges. Since voltage (change in electrical potential) is path-independent, any path between the two terminals of the battery has the same electrical potential difference or voltage. If we connect a wire from one terminal of the battery to the other, the voltage results in the Electrical Potential Energy of the electrons being transferred to movement as they move from one terminal to the other.
If we connect a capacitor to this circuit, the electrons move from the negative terminal of the battery to the negative terminal of the capacitor, and are stopped there by the dielectric. Eventually however, the electrons on the plates themselves form an electric field, which increases the potential difference between the capacitor. At some point the potential differences between the battery and the capacitor is the same, so no more electrons can flow.