So I can't just write a scene without the MC? Just to tell what's happening there? I need to write it through someone in 3rd person? I don't get this. Why?
Because people will foam at the mouth at you that you're doing it wrong.
If you write like this in say Russian, or French, or German, or Spanish--it's OK--the readers, editors, and publishers there are fine with that. That's how the novel has worked since the early 19th century, with no interruption in technique.
For the contemporary English-speaking market though, you have to keep in mind a whole arsenal of petty restrictions and 'rules' which apparently keep a lot of people in business, and help a multitude of amateurs feel they know how this stuff works when they memorize these 'rules'. They would include Show Don't Tell, No Head-Hopping, No Tense Shifts, No Passive Sentences, and others. When writing for the English-speaking market, you have to know this stuff inside out, in order to appease the gatekeepers of the business.
It doesn't mean they are right--if you would slap in front of them a copy of Anna Karenina, The Brothers Karamazov, or Dune or even Cujo--and demanded they
make these novels better by applying their precious little rules, like taking away the head-hopping and telling and passive sentences, etc.--they would try to change the subject--of course this would only destroy the novels. But--that doesn't change the fact that you--here and now--have to know these rules and quote them and apply them. Because that's the facts of life.
You
can take a flying dump on all these rules--but only if you're an obvious semi-genius, like Stephen King, Mario Puzo, Frank Herbert, etc. If, however, a gatekeeper sees more than two-three faulty sentences or misspelled words in the sample you send over, and sees also that you don't follow the contemporary Anglosax petty rules of writing--they could jump to the conclusion that you don't know what you're doing. It's much safer to play by the rules.
Learn to Google, too. When people here say "omniscient narration" and "close 3rd person"--check these things out. Don't think a one-sentence answer can help you. It won't. Read definitions and examples online. Read books written in those modes. Compare. Choose your personal style.
Out of the kindness of his heart Uncle Jim (search for Uncle Jim Undilluted) has written pages upon pages, to help people who are just starting out, where you can learn the rules and tricks you need to learn. Invest the time--read all this. Other people also share what they have learned through years of hard work. Jim Butcher had some insights on the web somewhere--locate and check out. Brandon Sanderson the contemporary sword and sorcery giant also gives tips on writing. Many writers in the English-speaking world share their hard-won knowledge for free. You'd be a fool to not drink in from every source, if you're in this for real.
Better yet--stick to 1st person. Many great writers like Chandler always stuck with 1st person and it worked out great for them. Or, if you really want to go Tolstoy omniscient where you can show anything you like at any time--start working on being impeccable, otherwise people won't believe you know what you're doing.