What is a velocity vector?
A vector has magnitude and direction. Whereas, a scalar simply has magnitude.
Velocity is defined to be a vector. Speed on the other hand is defined to be a scalar.
Since you haven't specified, a vector can be as simple as a 1D vector which is either positive or negative.
A vector can be more complicated using 2D. The vector can be specified as Cartesian coordinates, such as
In can still be more complicated in 3D using Cartesian coordinates, spherical coordinates, cylindrical coordinates, or others.
So, a velocity vector should be specified using one of the above coordinate systems.