Who would ever say "she is going to the lunch" in English. While technically not incorrect it is highly unnatural and certainly doesn't roll off the tounge. If I heard anyone contstruct their sentence like that, I would suspect that the person just learned English or didn't bother to learn it properly.
No, she is going to the lunch is a perfectly fine phrase to use in English. For example someone might ask: Is she going to the lunch? This would be said in response to an inquiry for example about a lunch that is being held as part of a function like a business presentation or meeting where it might be an option to attend the lunch. There are probably other good examples but this one is what comes to mind.
Well then, AndriLindbergs, you would be wrong - and very much so. The sentence "she is going to the lunch" is as natural as any other in English. You are not the right person to give English advice, as your spelling shows. Please refrain from doing so until you have become educated enough in the language, as currently you are likely to steer some learners in the wrong direction.
Yes... over time you'll learn what preposition i used after a verb and when it becomes necessary. That is a little thing and people wont be too annoyed if you cant use them pretty well at first. After all, there are other points which require more concentration and dedication.... leave this as a future subjective. Up to that time, learn some of them through your lessons ;)
I think this one means she goes to a specific event, like a planned business lunch. Demanding an article can be legit in that case. But it's still a terrible sentence because naturally everyone would assume she just goes to a regular lunch. That, then, will be "to lunch" or "for lunch".