If a publisher rejects your work, they will not be publishing it, pure and simple. However, it also means that you are at least getting your writing out there. I’ve lost count of the number of people I speak to who have written a novel and still not sent it out. Yes, you have to feel its ready and in some ways it never will be, but some people are so fearful of rejection that they never submit anything at all.
Rejections can often come with constructive criticism and suggestions for additions or improvements. Rejections also show that you’ve got the courage to actually send your work out and move toward becoming a professional writer. And once you have a rejection, you can of course now send it out to the next publisher on your list, preferably on the same day. Always have something out there doing the rounds, in my opinion. After all, some publishers can take six months or longer to reply. The more you submit, the more rejections you may receive, but the more chances you have of being accepted too. Someone once informed me that they never bought lottery tickets because they never won anything. Well, you’ll certainly never attract the attention of an editor or publisher if you don’t send anything out, so start submitting.