These are very basic terms used in Electronic Circuits.

Voltage can be defined as a type of Force which drives the electric current in the electronic circuit. Its unit is Volts. For example we have a 9volts battery.

Electric Current can be defined as flow of electrons in the electronic circuit. Electrons are nothing but a type of a charge. Its unit is Amperes.

Resistance is the obstruction in path of current. It is measured in Ohms.