What is the meaning of "Or the other way around" in below sentence I sow in newspaper.
You read a book & tell someone you loved it & they go pick it up. Or the other way around.
The phrase "the other way around" is synonymous with the originally Latin phrase vice versa, which means "the same is true if you reverse the order of the constituents" (making whatever changes are necessary to the grammatical case):
I like her and vice versa (that is, and she likes me).
I like her, and the other way around.
With your example:
You read a book & tell someone you loved it & they go pick it up.
The other way around:
Someone reads a book and tells you that they loved it, and you buy a copy of it.
The other way around would be:
Someone picks up a book that you have read, and you tell them that you loved it.