杯子 (bēizi) is the standard Chinese word for "cup" or "glass," referring to a drinking vessel. It is commonly used with measure words like 一个杯子 (one cup) and frequently appears in phrases describing what a cup contains, such as 杯子里的水 (the water in the cup).
请帮我拿一个杯子,我想喝水。
Qǐng bāng wǒ ná yī gè bēizi, wǒ xiǎng hē shuǐ.
Please get me a cup — I'd like some water.
桌上那个杯子是谁的?
Zhuō shàng nà gè bēizi shì shéi de?
Whose cup is that on the table?
小心点,杯子里的咖啡还很烫。
Xiǎoxīn diǎn, bēizi lǐ de kāfēi hái hěn tàng.
Be careful — the coffee in the cup is still very hot.