This is a very common and polite welcome greeting used by staff in shops, restaurants, or hotels to customers. It means "Welcome" or "May I help you?" and is used to invite customers in and signal that service is available.

お店やレストランなどで、店員がお客さんを歓迎する時に使う丁寧な挨拶です。「ようこそ」や「何かお手伝いしましょうか」という気持ちです。