A spoileron is a combination of an aileron and a spoiler. They are often used on faster aircraft where the additional drag generated by the lowered aileron would be unacceptable. Instead, a single wing’s spoileron is raised, which reduces the lift on that wing, causing it to drop and the aircraft to roll in that direction. The spoileron on the other wing remains in place, eliminating any additional drag that would’ve been caused by an aileron.