明星 (míngxīng) means a star or celebrity. It is used to describe famous people, especially in entertainment and sports. For example, 网球明星 means "tennis star."
他是中国最受欢迎的电影明星之一。
tā shì zhōngguó zuì shòu huānyíng de diànyǐng míngxīng zhī yī.
He is one of the most popular movie stars in China.
很多年轻人都梦想成为明星。
hěn duō niánqīng rén dōu mèngxiǎng chéngwéi míngxīng.
Many young people dream of becoming a star.
那位网球明星今天在机场被粉丝包围了。
nà wèi wǎngqiú míngxīng jīntiān zài jīchǎng bèi fěnsī bāowéi le.
That tennis star was surrounded by fans at the airport today.