Vectors are physical quantities that can be defined, measured , worked up on using a vector algebra. These quantities have a magnitude like distance etc. Not only that vectors have also a direction associated with them.
Gravitational force of earth is always directed towards center of earth. It has a direction. Its impact on people is not same in any other direction. Velocity is a vector whose e magnitude is the value of speed and direction is the one in which the person or object is moving. Suppose we take velocity of a train - if is approaching us we see more and more clearly and its whistle sounds & is heard differently. When the train is going away from us. It is heard differently and its size reduces i n our view.
There is an impact of direction on some physical quantities. So we define vectors.
force , velocity, friction force etc. have a direction. they are felt differently in different directions.
pressure does not ahave a particular direction. it is same for all directions at a height in water or air. it is not a vector.