Represent vectorially a velocity of 10m/s.

A velocity vector represents the rate of change of the position of an object. The magnitude of a velocity vector gives the speed of an object while the vector direction gives its direction. 
$$\begin{gathered} As velocity = displacement/ time interval \\ \stackrel{\rightharpoonup }{v} =\frac{d\stackrel{\rightharpoonup }{x}}{dt} \end{gathered}$$

You have not specified the direction of velocity.