Linear perspective is a technique to reproduce in drawing the convergence of lines that we naturally perceive with our human vision. It is one of the ways to reproduce the illusion of depth.
If we represent a volume without considering perspective, the illusion of depth will only work partially. Sometimes this is enough, but most times it isn't.
We can clearly see that the opposite face has remained the same size as the front - there isn't the shrinking that we would naturally perceive.
To draw a cube in perspective, we will make the front face as in the example above, but with the difference that we will make the lines converge at a point placed on a horizon line.This time, the back face will be smaller than the front face.
A house, a car, a character - once the horizon line and vanishing point are placed, all we have to do is to always consider this vanishing point when drawing each volume.
Begin by mastering perspective with one vanishing point. Move the horizon line to see how it changes the view. In the street, also learn to identify vanishing points before drawing the details of a street, a building, etc. Once you are more comfortable with one essential vanishing point, you can start placing two vanishing points, and then 3, as in the example opposite. This is a rather particular perspective - two main vanishing points are usually sufficient for most designs, though you still have to learn how to draw this style of perspective.