There's some missing context here, but I would guess you're talking about a box or something with some mass m being pushed over a flat surface. Since it's moving with constant velocity, there is no acceleration and so the box is in equilibrium. In particular, the horizontal forces cancel each other. If f is the magnitude of the friction force, then
17 N + (-f ) = 0
f = 17 N
and this force points opposite the direction of motion.
