Pronounced as: sin jow, the word "chào" means hello in English, but you would rarely use it alone.
Typically, you would need to follow the term with another word based on the age, gender, and familiarity of the other person.
Adding "xin" to the front of "chào" makes the phrase more polite. Native Vietnamese speakers would typically reserve this for someone who is older or admired.
So the next time you come into Que Việt, remember to say xin chào to our staff!