Meaning of the word "don't open a shop unless you know how to smile" in English

What does "don't open a shop unless you know how to smile" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

don't open a shop unless you know how to smile

US /doʊnt ˈoʊpən ə ʃɑːp ʌnˈles juː noʊ haʊ tuː smaɪl/
UK /dəʊnt ˈəʊpən ə ʃɒp ʌnˈles juː nəʊ haʊ tuː smaɪl/
"don't open a shop unless you know how to smile" picture

Idiom

a proverb suggesting that one should not engage in business or public-facing work if they lack a friendly and welcoming attitude

Example:
If you're going to be grumpy with customers, remember: don't open a shop unless you know how to smile.
Customer service is all about attitude; as the saying goes, don't open a shop unless you know how to smile.