Physical quantities fall into two groups. A scalar quantity has magnitude only, which means it is just a size with a unit. Mass, distance, speed, time, energy and temperature are all scalars. Saying a car has a speed of 20 m/s tells you everything there is to know about how fast it is going.
A vector quantity has both magnitude and an associated direction. Force, weight, displacement, velocity and acceleration are vectors. Velocity is speed in a stated direction, so 20 m/s north and 20 m/s south are different velocities even though the speed is the same.
A vector can be drawn as an arrow. The length of the arrow shows the magnitude, so a longer arrow means a bigger vector. The direction the arrow points shows the direction of the vector.