The joule (J) is an SI (derived) unit of energy equivalent to
the work done by the force of a newton (a unit
of force) pushing over a meter distance.
A joule is one kilogram meter-squared per second-squared
(kg·m²/s²),
a newton being the force necessary to accelerate a kilogram
one meter per second-squared.
This is very roughly the energy to lift (in Earthsurface gravity) a pound weight 9 inches, or a kg weight 10 cm.
A joule is also a watt-second.
107ergs make a joule.