It ain't that hard once you get used to the notion that your body's weight is a measure of force, which you apply to your bathroom scale with the help of gravity. Unnoticed under usual day-to-day circumstances, gravity is accelerating your body toward the center of the Earth, roughly. Fortunately, you have floors, sidewalks, and the surface of the earth itself to prevent this acceleration from happening, but if you jump off a step stool at, say, one meter (a yard more or less) high, and then jump off a table that is 6 feet high, you will notice a dramatic difference in the force when you hit. That's the same force as your bathroom scale measures, but since you don't leap onto your scale from a foot up, I hope, it measures the force you apply to it in a more genteel manner.
If you were on the moon, your weight would be much less. Your scale would show you it was so.
But your body's mass would be the same. Mass is essentially the tendency of a body to resist acceleration, according to some definitions. Anyway, an object may weigh one thing at sea level in North Carolina, another thing on the Moon, and something else at the top of the Himalayas, but the mass of the object won't vary.
This value of "g" is just an approximation of how much acceleration (speeding up from zero start) gravity puts on an object when it falls freely. It starts at rest, so its speed is zero meters per second. The gravity field instantly starts acting on it so that after one second its speed is about 9.8 meters per second. After two seconds, it is going 10.16 meters per second. Every second of free fall increases the speed of the object falling in Earth's gravity by another 9.8 meters per second. This rate of speeding up is called "accelerating at (9.8 meters per second) per second". Or, 9.8 meters per second squared, speaking loosely.