This can either be a neck or a bridge alignment. If you just noticed this and it didn’t happen before, check the condition of the instrument for any broken joints or damage. This is very typical on Fender style instruments and can happen if the instrument is dropped or bumped in the case. With my Fender, if the strings are near the edge on one side, I would slightly loosen the four neck screws and carefully pull the neck towards the side. This will help align the strings evenly on both sides of the fingerboard. This will align the strings better over the pickups too. If you have an older arch top guitar, the bridge may actually slide from side to side. I would loosen the strings and gently align the bridge to the proper position where the strings are even on both sides. There can be other important details, but they should be evaluated by a qualified repairman.