What do you mean by staying late?

It means not arriving at the scheduled time, but later than the scheduled time. Late check-in means that when you check into a hotel or hotel, you must check in later than planned. For example, after 10 in the evening, most hotels are considered as normal check-in before 10 in the evening, and failure to arrive after 10 in the evening is considered as failure to arrive at the scheduled time, which belongs to delayed check-in.