The book should be easy to read, or at least average. The level for reading such a book is the MATH and CS school curriculum. It should also be expanded on topics related to CS, and also be narrated in a light manner. It should be kind of in a intro tutorial before starting a middle combinatorics.
[From you comment] P.S need such combinatorics after which I can understand the course of data structures and algorithms.
Combinatorics don't factor into data structures and algorithms in this way. If your goal is to understand data structures and algorithms, combinatorics are an irrelevant topic.
Combinatorics is also quite vague, as this can effectively include the integer number sequence, which is effectively "knowing how to count".
While software development will generally expect you to count numbers from time to time, there's a vast difference between counting and the subjects that a book on combinatorics will delve into. Again, the latter is irrelevant to get a basic understanding of data structures and algorithms.
Is there a good book for combinatorics for programmers?
As far as I'm aware and my research could uncover, there is no such book tailored to software engineers. The field of combinatorics is not part of the field of software engineering. Combinatorics are a part of maths, not CS, and therefore are explained in a mathematical context.
Note that it is true that early examples in CS training courses often use simple maths. However, this is done purely because students will generally understand the simple maths and therefore are able to fully focus on the programming challenge without being distracted by the mathematical operations in the example.
If you are able to count and perform elementary operations (+,-,*,/) then you have enough knowledge to learn programming. Additional mathematical operations may be a nice-to-have for more advanced examples, but they don't require an in-depth mathematical skill. If you passed high school maths (based on my experience, you don't need anything above the math 14-year-olds are taught in school), then you are as prepared as you need to be.
Obvious caveat: Unless your intention is to delve into programming specifically to tackle more advanced mathematical calculations. But that's not what a learner should be focusing on.