Meaning:

“玻璃” means “glass,” and “心” refers to “heart.” In Chinese, “heart” is another word for “mind” or “emotion.” Chinese netizens coined this term to metaphorically refer to a person whose heart is as fragile as glass and easily hurt by what others say. In a word, you can use it to describe those who are overly sensitive and very easily take offense by another’s thoughtless jokes or teasing.

Example:

A: 为什么丽丽好几天不理我？

Wèishénme lìlì hǎojǐtiān bù lǐ wǒ？

Why has Lili been ignoring me for several days?

B: 因为你当着大家的面叫她小猪佩奇。

Yīnwèi nǐ dāngzhe dàjiā de miàn jiàotā xiǎozhū pèiqí。

Because you called her Peppa Pig in front of everyone.

A: 她也太玻璃心了吧，我只不过开玩笑说她喜欢穿粉色衣服。

Tā yě tài bōlixīn le ba，wǒ zhǐbúguò kāi wánxiào shuō tā xǐhuān chuān fěnsè yīfú。

She is so easily offended. I was just joking about her liking for pink outfits.