Before Newton, it had been widely held that objects have a natural tendency to stop moving. Newton recognized the role of friction is stopping things, and realized that friction is itself a force. Another consequence of Newton's first law is that you need a force to change the direction of a motion, such as in going around a bend or around an orbit. This is the most mathematical of the laws. The force could be a push, a pull, gravity, magnetism, air pressure, friction, or whatever.
Acceleration is the change in velocity with respect to time.
The mass of a body is the amount of matter it contains. Loosely speaking it is the same as the body's weight. The mass is not the same as the volume, which is essentially the size of an object. If a handful of shaving cream expands its mass stays the same, but its volume increases. The link between mass and volume is the density .