I try to make my first patent (a machine/construction) in my country. Here is how things are, I thought of an idea I constructed, it is fully operational so I make a request with the data to the patent office (including the description I made, the schematics, the claims). The patent office sends me a file with patents that have some claims the same/similar as mine, either part of them or all of them, but these patents exist on US, China and one international patent (the last one covers 3 out of 9 of my claims). None of them is a patent in my country. So my question what is the purpose of the composition that the patent office sends to me? What should I check/see?
You don't state your country, but the general rule is that prior art anywhere in the world is prior art everywhere in the world. Thus you can't just patent in your country an invention found in any other country. This is not limited to patents. Any invention that is publicly disclosed is prior art.
I always suggest working with a patent attorney when drafting patents. Writing claims that are effective is difficult and requires experience and legal knowledge. While you see patents with similar claims, they may not be truly the same invention. In nearly every one of my patents the patent office cited prior art. With my patent attorney, we explained why that prior art was different from my inventions and in nearly every case obtained a patent.
Also, I should point out that if there are no patents covering your product in your country, you can sell the product in your country without fear of infringing a patent even if you don't obtain a patent yourself.
Usually a patent office will make you aware of publications, patents and patent applications that tend to show that your claims are either not new (not novel or anticipated) and/or are obvious (lack an inventive step or element). Any document published anywhere in the world in any language at any time before you filed can be used to show that your idea is not new.
Along with it should be a search report or rejection that spells out how aspects of the publications map onto your claims and give you a time period to reply. To get the patent you need to either amend your claims to only included novel and non-obvious claims or argue why the publication do not show what the examiner thinks they show.