A guest or visitor — a polite way to refer to someone who visits.
今日はお客さんが来るから、部屋を片付けておいてね。
Guests are coming today, so tidy the room, please.
友達をお客さんとして迎えたわけではないが、丁寧にもてなした。
It wasn't a formal visit, but I treated my friend politely as a guest.
お客さんが増えて、店は忙しくなった。
Customers increased and the shop got busy.
A customer, client, spectator, tourist, passenger, etc. — someone receiving a service or attending an event.
レジでお客さんが並んでいるので、対応を急いでください。
Customers are lining up at the register, so please hurry with service.
観客が満席で、お客さんは大盛況だった。
The audience was full; the event was a big success with attendees.
観光地には毎年多くのお客さんが訪れる。
Many tourists visit the sightseeing spot every year.