The book's motion is governed by both Newton's first and second laws of motion.
And if you push on the book, and you're exerting the only external force on the
book, it accelerates in the direction of your push and it's velocity changes with
time. If you stop pushing on that book, it
becomes inertial. It's experiencing no overall external
force, and it coasts. Friction, and air resistance as well, are
nuisances, and they interfere with inertial motion.
They make the whole idea of coasting seem counterintuitive.
You've never seen a file cabinet or a carpet or a glass of water even, coast
horizontally across a horizontal surface. You have to push them the whole way, and
when you stop pushing, they very quickly come to a stop.
But that's not because Newton's laws are wrong, it's because of friction.
It sure seems like you have to push on something to make it move, and when you
stop pushing it comes to a stop. But that's just friction messing with
your head. If you use skates to eliminate friction,
so that friction can't interfere with inertial motion.
Then an object, namely the skater, can be truly free of external forces.
Or, least overall external forces. And can move according to Newton's first
law. And when something pushes on that skater.
So the skater experiences a net force. That net force causes the skater to
accelerate and the skater's velocity changes according to that acceleration.