Question

what do you mean by newton first law

Answer 1

$newtons \: first \: law \: of \: motion -$

a body at rest will remain at rest and a body in motion will continue in motion in a straight line with a uniform speed unless it is compelled by an external force to change its state of rest or of uniform motion.

Newton's first law of motion gives us a definition of force.
it says that a force is something which changes or tends to change the state of rest aur of uniform motion of a body. in other words a force is an influence which can produce an acceleration or retardation in a body.