Oh, kumis (кумыс). As a person from Kazakhstan🇰🇿, I know very well what is it. Lovely fermented horse milk. It's our national drink though.
It's very healthy and everyone can drink it. And, I can say, it's tasty (?). But for unprepared person the taste will be too strong.
Ah, also it's not so alcoholic as you can imagine. About 1% or less