The phrase 'Business Opportunity' almost always refers to a nasty, but somehow legal (due to its being ostensibly a business about selling overpriced product) pyramid scheme that's been running for almost 50 years and has helped thousands of people get wealthy at the expense of thousands of others who have lost a great deal of time and money chasing a phoney dream.
They have clever recruiters who will try to convince you that being an MLM rep for a large company is somehow the same as being an 'Independent Business Owner' and that this is the sure path to living in a huge house, driving an expensive sports car, and getting to spend all your time with your gorgeous wife because you will make so much money with so little effort that you can quit your day job.
If a stranger is talking to you and mentions that they would like to discuss with you a 'Business Opportunity', don't walk away, RUN!
Recruiter: Golly Joe, it was sure great meeting you today, but I was wondering if we could get together some time so I we can discuss an exciting business opportunity that I've recently become involved in.
Translation: You seem like a relatively gullible person, so I'm going to try my hardest to suck you into this horrendous disaster of a scam so me and my associates can take away as much of your money as we can until you realize you've been had.