Complex sentence: The voltage between two points is equal to the work done per unit of charge against a static electric field to move the test charge between two points and is measured in units of "volts" (a joule per coulomb).
Split into simpler sentences: The voltage between two points is equal to the work done per unit of charge against a static electric field to move the test charge between two points. This is measured in units of "volts" (a joule per coulomb).