Oh, what a gorgious lady you got! Both she and you are winners here.
She is adult, may be even 5+. But exact age is impossible to say. Ask your vet when you make a vet visit. His guess will be best here.
Breed? Breed is not about looks, but about ancestry. 97% of cats arent any especial breed, they are result of the genes floating in the gene pool of the local cats.
So the safe to say, is she is a domestic long hair. Tabby.
What look alike? It depends on where you live. If you live in Germany, a nice comparison would probably be the German Longhair (look for them in our other Forum for breeders).
If you live in Russia - the Sibirian.
If you live in USA - it would be the Maine Coon, or rather, the natural population of long haired cats, often tabbies, from which the Maine Coon got purebred from.
For color / pattern, I think she looks like a Brown Torbie ( tortie - tabby). I also was reminded about the discussion of German Longhair. but she wouldn't be that if she's from somewhere far from there.
As Stefan says, most cats really aren't considered a specific breed. It is very different from dogs, that have had a lot more human control over their breeding.
Yep, after googling "brown torbie maine coon" it looks like she's closest to those. I feel so lucky. The Maine Coon has a really interesting history. I can't believe they were almost extinct in 1950! They are so beautiful.
She is really very quiet and gentle. She hardly ever meows, and when she does it is very soft.