三 + Measure Word + Noun
三 (sān) is the number "three" in Chinese. Like all Chinese numerals, it appears before a measure word when counting objects, as in 三个 (three items). It can also appear in time expressions like 三年 (three years) and 三月 (March or three months).
我买了三个苹果和三瓶水。
Wǒ mǎi le sān ge píngguǒ hé sān píng shuǐ.
I bought three apples and three bottles of water.
他们三个人一起去旅行了。
Tāmen sān ge rén yīqǐ qù lǚxíng le.
The three of them went traveling together.
这道菜只需要三分钟就能做好。
Zhè dào cài zhǐ xūyào sān fēnzhōng jiù néng zuò hǎo.
This dish only takes three minutes to prepare.