It is an idiomatic expression. 계타셨네요: It's usually used when you think someone is really lucky because something good happened to the person. So, 계타셨네요 means "You're in luck."

계(契) is a private funding scheme traditionally popular in Korea, especially among women. The fund manager(계주) gathers participants and sets up the monthly payment and payout sums and schedule. For example, a 계 of 50 participants would have all fifty of them make a set monthly deposit for fifty months, while one of them takes a lump sum payout each month according to a preset schedule. Receiving this payout is called "계(를) 타다", "타다" here meaning "receive" or "win". So "계 타셨네요" means "You received a 계 payout". Obviously it is a big thing since the receiver gets her hand on a large sum of money she has been anxiously waiting for.