This is a story about a Punjabi boy falling in love with a Tamilian girl and how they go about trying to convince the parents of each other so that the parents give their consent for the marriage. That’s the overall plot. You will have to read the book to know what happens at the end.
But the question is whether you should read the book?
I would say that this book is definitely not in the "must read" category. You could consider it a light read without expecting much from it but first the positives, overall the story has a good pace and the first half makes and interesting read. Characters are simple with whom we can easily relate to and the language is very easy to follow.
The first half of the book is quite interesting and has some humor too. But after that the story is completely predictable. Situations seem copied right from some Bollywood movies. (might be an after effect of "five point someone" being converted to the movie "3 idiots". Also Tamilians / Punjabis might feel slightly offended by the way they have been depicted in the book.