Number + 月
In Chinese, months are expressed using a number followed by 月 (yuè). For example, 五月 means "May" or "the fifth month." In the context of the lunar calendar (农历), 月 refers to lunar months, which may differ from the Gregorian calendar months.
我的生日在三月。
Wǒ de shēngrì zài sānyuè.
My birthday is in March.
七月和八月是最热的两个月。
Qīyuè hé bāyuè shì zuì rè de liǎng gè yuè.
July and August are the two hottest months.
她打算十二月去日本旅行。
Tā dǎsuàn shí'èryuè qù Rìběn lǚxíng.
She plans to travel to Japan in December.