How three phase and single phase actually work?

I am finding very difficult in grasping every problem quickly.... So I just want to know it.

@Aravind‍ - have you referred to the textbook? It should explain it in detail. Better, you could ask what specific part you found hard to follow. I'd recommend starting with this video to understand 3-phase power -

https://www.youtube.com/watch?v=4oRT7PoXSS0

single an three phase supply working - nptel :

https://www.google.co.in/search?q=single+an+three+phase+supply+working+nptel&ie=UTF-8&oe=UTF-8&hl=en-in&client=safari

I have project in this semester so please give ideas related to the exhaust gas reuse.