"6.5 km/hr" is not a velocity. It's just a speed, so we don't know what direction he's walking.
If he happens to be walking north, then it takes him
(12 km) / (6.5 km/hr) = 1.846... hours (rounded) .
If he's walking in any other direction, it takes him longer than that.
If the angle between north and the direction he's walking is 90 degrees or more, then he can never cover any northward distance, no matter how long he walks.
