ie. 1 Earth Gravity, where 1Kg Static Mass = 1Kg static weight. Simply put, gravity is acceleration, at the earths constant speed we experience 1G in daily life, around 9.8m/s2 (metres per second squared). If we accelerate in a car or plane, or simply by running we experience greater 'G' by increasing our acceleration.
see http://en.wikipedia.org/wiki/Gravity for a full & technical explanation.
ps. This really is not the correct site for science related questions! This is an English Language Forum. Try Wikipedia for any other technical data.