月 is a picture of the crescent moon — the moon was usually drawn as a crescent because a full circle was already taken by the sun (日). The two inner strokes are its markings. One cycle of the moon = one month, so 月 means both 'moon' and 'month'.
The moon is deeply romantic in Chinese culture. The Mid-Autumn Festival (中秋节) is all about the full moon, family reunion, and mooncakes. The poet Li Bai wrote some of China's most famous lines gazing at 明月 (the bright moon). Months are simply counted: 一月 (January, 'month one'), 二月 (February)...
A crescent shape with two marks inside — the MOON in the night sky.
Confusingly, a second 月-like shape (called 'meat radical') appears in body-part characters like 脸 (face) and 胖 (fat). Same shape, different origin — context tells them apart.