Facebook Groups are good places for sharing, discussion and networking. They are also a gold mine where you get plenty of opportunities to earn revenue. For example, you can sell the stuff that may not be useful for you anymore but can help other people. For both sellers and buyers, it is a gain.
There are also many other ways to monetize Facebook Groups. You can see them in this article.
1. Buy and Sell
There are plenty of "Buy and Sell" groups on Facebook, from baby clothes to second hand cars. Those groups are awesome because they give people an alternative choice to find what they need and to buy good stuff at a lower price. They also let people who share the common interests exchange information and find the best offers.
For local community, you can exchange your stuff and build relationship. For commerce and business, you can get in touch directly with your customers and drive sales.
2. Propose service
Like "Buy and sell" groups, there are also many groups for people to propose services or find jobs. Those groups are awesome for freelancers, job seekers, headhunters, HR consultants...
You can propose your freelance service (web design, SEO, writing, graphic design...), carpooling, home service, babysitting, teaching... and get paid for your work. You can also create your own service groups where professionals in your field can exchange insights, experiences and opportunities.
3. Drive traffic
If you have a website, a blog or a Youtube channel, Facebook Groups can help you drive traffic.
You can share your links in group posts or comments. Write a short story to tell people what it is about and include a call-to-action to invite people to take a look. If group members like what you share, they may also share it in other groups or on their personal timeline. In this way, you can drive traffic to your blog or site, or get views for your videos to get paid.
4. Get paid per post click
If you work for your customers and help them get traffic to their sites, YouTube Channels, Facebook pages and groups, then you can explain to them how you get visitors and targeted audience for them and get paid per post click.