When you scold someone, you (often angrily) point out and criticize some fault or error. If you forget again to clean up your room, your mom might scold you for it.
Scold can also be used as a noun to describe a person who irritates people by finding fault in everything. Your great aunt Merna, who during the holidays complains about her gifts, criticizes your weight, says the turkey is too dry, and the stuffing is soggy? She's a scold. Maybe she's cranky. Which brings us to the other way we can use scold as a verb: to grumble, grouch, or generally express one's crankiness. This latter meaning has more to do with the attitude of the scolder than the faults of the one being scolded.