The Force is a power that binds all things in the universe. Those who are sensitive with the Force can feel it flow through the world and even manipulate it with training. Rey was largely unaware of her affinity with the Force until she heard the call of Luke Skywalker's lightsaber deep in Maz Kanata's castle. She discovered even more abilities after Kylo Ren attempted to interrogate her and failed.
Rey gained years of experience working with machinery from a young age. She scavenged technology that had been scattered over Jakku, and selling what she could repair. Her talents with engineering even allowed her to build her own repulsorlift speeder and modify a downed AT-AT into a living space.
Rey used piloting simulators to teach herself to pilot various vehicles, and had practical experience with her personal speeder.