Others are providing a reasonable answer to the question you asked (how does admissions work?), but I wonder if the question you meant to ask is "How should I interpret that professor's comment? Does this mean I'm very likely to be admitted?"
I'll help you interpret the professor's comment. The answer is... it's very hard to read anything into that comment. It could mean anything from "That professor is very excited about working with you and plans to advocate for your admitted (so you're likely to be admitted) but he wants you to know he can't make any guarantees" to "The professor feels that you are within the plausible range of someone who might be seriously considered for admission, so he is encouraging you to apply" to "The professor suspects admission might not be a slam-dunk or might be a long shot, but for politeness or other reasons doesn't want to come out and say that, so he is giving a veiled warning by noting that the admissions committee makes all decisions" to "The professor has no interest in working with you or advocating for your acceptance but there's no harm in encouraging you to apply", or anything in between.
The bottom line is that if you are interested in studying at that school, I definitely recommend that you apply. The one sure way to guarantee that you won't be admitted, is to not apply. So, do apply.
But don't read too much into the professor's comments. You should not interpret this as a statement about your chances of admission. Actually, at this point you shouldn't really speculate about your chances of admission -- it's not very constructive. If it's not going to change anything you do, it's not worth worrying about. And there are many factors that go into this that you can't predict.
The procedures followed by the admissions committee don't really change my remarks above. Yes, in many fields, if the professor wants to advocate for your acceptance, the admissions committee will probably go along with that (barring any serious red flags). But even admissions works that way at that school, this doesn't mean that the professor is necessarily going to advocate for your acceptance. All he said is that he encourages you to apply -- a generic statement that many professors will routinely make to anyone who expresses interest, and certainly not a promise that he is going to advocate for your acceptance.
Bottom line: Again, there's not much point to speculating about how likely you are to be admitted. It's unlikely anyone can give you an answer to that without much more detailed information -- and it's not a useful or constructive thing to worry about. There are so many considerations that can affect whether you are admitted, which don't necessarily have anything to do with you. My advice is, apply to a reasonable set of places that you would love to study at and you have a reasonable chance to be admitted to, and then just wait and see what happens. Don't get yourself too caught up in speculating what might or might not happen.