Is it a yamaha ybr 125? If so that lock holds the side panel on, the battery and a small tool kit are under the panel It is one of three contact points holding the panel on, the other two are above it at either end of the panel - carefull taking the panel off as the one towards front of the bike is a peg which snaps easily, the one towards the back is a hook which also snaps easily Similar story on the other side only it's a screw in place of the lock and that panel hides the air filter In order, open the lock/remove screw, gently prize the peg out of it's slot - try getting your hand behind the panel and pushing it out rather than pulling it, then pull the panel gently towards you and towards the front of the bike to release the hook Hope this helps Sent from my MB525 using Tapatalk