Clarkson, 31, recently visited coffee farms and performed a special set for farmers and their families in Peru.
"It was so funny cause I didn't know if they were gonna like my songs. They would sing along, I think we did like a mini-set for them, so we did a few songs down there. They were dancing, it was just so cool! I felt like I was just in a movie," Clarkson tells PEOPLE of the performance. "I was dancing with them!"
Her trip, part of Green Mountain Coffee's Great Coffee, Good Vibes, Choose Fair Trade campaign, was an eye-opening experience for Clarkson.
"I didn't know that a lot of them didn't have electricity," she says. "That's the one cool thing that was for me to learn with this opportunity, [through Fair Trade] they have more opportunity with their whole community. They have more education and more access to electricity. It's a better way to further the community. I felt like I was actually making a difference, which is something I think we all want to be a part of."
While the acoustic performance brought Clarkson's audience to their feet, the singer says she couldn't quite keep up with their moves.
"I couldn't do their steps," Clarkson confesses. "I was totally not Beyoncé. They all had these cute dances they were doing together… I just started doing the sprinkler and the running man."
But when it comes to dancing on her big day – her upcoming nuptials to fiancé Brandon Blackstock – the singer has the perfect song all picked out.
"We're bringing our own vinyl player and we're doing it that way. Eva Cassidy is like my favorite, and her song 'Songbird' so we're probably gonna slow dance alone to it," she says.
Though she says the couple is "already basically married," she's ready to start the next stage of her life with Blackstock by her side.
"We live together. We have a house together. We have the two kids who live with us. We're already kind of a family. But I think that it just kind of puts it in place. When you get married, it's like official. You're starting a family and we want to have more children, so we're just excited. I guess that's the best part, it's a new kind of chapter in my life."
In celebration of Fair Trade Month (October), Clarkson will perform a private concert at the High Line Ballroom in New York on Oct. 10. Viewers can tune in to watch a livestream on Green Mountain Coffee's Facebook page at 8:30 p.m. EST.