By definition, we have that the speed of an object is given by:

Where,
d: distance [in units of length: meters, feet, miles]
t: time [in units of time: minutes, seconds, hours]
Therefore, knowing the distance traveled, and the time to travel this distance, we can know the speed of an object.
Then, since velocity is a vector, then we need the direction of the vector.
Therefore, the velocity vector can be written as:

Answer:
two things you need to know to describe the velocity of an object are:
1) Magnitude (speed)
2) direction