What is the value of g

It depends on the environment around you ... the number and size of

the masses around you, and your distance from their center of mass.

If you happen to be on the surface of the Earth, then

g = 9.8 m/s²

or

g = 9.8 newton/kilogram.

It's different on other planets. Be sure to look it up

before you leave, so you'll know what to expect.