Awesome! Friction occurs whenever a body moves or tries to move on a surface. If an object is just sitting on a surface, there is no friction.

Once we exert a force to the right, the force tries to move the block to the right. But then the surface exerts a frictional force on the block in the opposite direction. Because the net force is $$0$$, the block doesn't move.

As we increase the force, the frictional force increases accordingly. Once we exert a force beyond the maximum frictional force possible ($$30 \, \mathrm{N}$$), the block starts to move.