The Vietnamese word "khách" is a noun that primarily means "guest," "caller," or "visitor." It refers to someone who comes to see or spend time with another person, or someone who visits a place, such as a shop or restaurant.
Khách đến thăm nhà tôi.
(A guest is visiting my house.)
Cửa tiệm này có nhiều khách.
(This shop has many customers.)