What Does G Stand For
G was measured by Cavendish to have the value of 6.673*10^(-11) Newtons of meters^2/kilogram^2. Which is not only used in Newton’s law of gravitation but and also in Einstein 's theory of relativity as well.
G is also used in the formula F = G*M*m/r^2.
Both m and M are masses of two bodies interacting gravitationally.
r is the separation of their centers of mass.
F is the force of gravitational attraction between them.
G can also represent local or global gravitational field. Which represents the force of gravity per unit mass acting on an object.
Gravitational field = 10 N/kg (Near Earth) either local or globally average
G may also represent free-fall acceleration or acceleration of gravity.
Free-Fall Accleration = 10 m/s2 (On Earth )
G refers to the metric prefix Giga as well. Such as in GHz for GigaHertz. Where Giga represents one billion.