Before reading this post you should have learned the main effects.
If you look at the picture depending on the numbers the more sideways the more spin you put on the cue ball.
When you hit the cue ball with low speed in the center on the right side the cue ball goes out of its center and a little to the right, there is a small deviation.
When you hit the cue ball with more speed, i.e. harder, the cue ball goes straight down the center, it has a little deflection and when it hits the rail it goes more to the right or vice versa.
One thing is difficult and that is to estimate the amount of deflection that you must give to the cue ball, you will know it by practicing a lot, that is, through your playing experience.
The side spin is very useful for shots close to the rail.
An example is this gif.
You must aim at the center of the object ball and with a lot of English in the center to the left you will see how you will make a perfect fine.
It is also useful to place the cue ball where you want, there are some shots that need that spin to avoid hitting the cue ball.
With the side spin and when you hit the cue ball with the rail there are three angles of opening or closing, accelerating or decelerating:
The amount of left or right English, open or close, will depend on the amount of English you put on the cue ball.
Next do the exercises to master these effects: