Fundametals with easy understanding ( EG)

Maybe if you tell us what you think they mean we'll help you out, but for the moment it looks as if you have applied no thought to the question yourself.
Start by working out mass and weight maybe by asking yourself the question. I you take a brick to the moon does it's mass change? Does it's weight change? (hint the answers are no and yes, respectively...)
Del

Go to your nearest library and get a high school physics book.

There is no easy understanding -- but there is this:

http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html