What does it mean when I guy says that he's a bachelor?

[D]

A Bachelor is best defined as a man who has no current planned commitment to a long term partner. You could on some level class him as being AVAILABLE.

Single,Unmarried, not in a relationship, are the terms that people usually associate with bachelors, but are inaccurate these days.

What he is (or at least should be) implying to you that he is available to explore he situation between you and that it will mostly be a casual and fun. Bare in mind he may well have other women he is seeing casually at the same time that you are unaware of, hence why saying not in a relationship cannot be entirely accurate.

Now just because he might want to see you casually and other women as well, doesn't mean he has no intentions of making it exclusive, that's up to you to make him want that but is always a possibility, usually men like that are well refined and fun to be around so even if nothing comes of it you may well have a fun and memorable time.