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Huānyíng guānglín
Firstly, lets break down the phrase.
出 means “going out” or “exit” as a verb;
入 means “coming in" or “enter” as a verb;
平 means peaceful, peace, harmony, harmonious, tranquil, etc
安 means safety, safe, security, secure, stable, etc.
Now, combine the first two Chinese characters, it means “going outside and coming inside”;
Then 平安 should be combined as together to form a new meaning as “safe and sound as in an intact piece”;
Now combine all these four together, it means “going out(side) and coming in(side) safe and sound in an intact piece”.
This is commonly found in restaurant entrances and also on doormats of people houses. It is a very common chinese phrase and is something that everyone learning Mandarin Chinese has to learn!