This is the 7408th most frequent Chinese word.
萧
"萧" means "desolate," "melancholy," or refers to a surname or a type of flute (vertical bamboo flute).
In this sentence, '萧萧' is used to describe a sound, often connoting a sense of melancholy or eeriness.
山间的夜晚，风声萧萧。
The sound of the wind is mournful during the mountain nights.
Here, '萧' refers to a traditional Chinese vertical bamboo flute, used as a noun.
他善于吹奏一种古老的乐器 — 萧。
He is skilled at playing an ancient musical instrument — the xiao.
In this context, '萧' is used as part of a personal name.