Bats and good luck
Homophone is a word that is pronounced the same as the other one but it has different meaning. All languages have such words. Mandarin Chinese has many homophones.
Very good example is Chinese word fú means a bat. Fú is also a word that means good fortune. These words have different Chinese characters but the present similarity contributed to the fact that bats are considered as symbols of good luck.

Bat carving in Guangzhou, China
Usually more than one bat symbol can be seen. Two bats or "shuang fú" means double luck. Five bats signify Five Fortunes - Good Luck, Prosperity, Wealth, Happiness, Longevity. Colour of bats plays an important role too. Chinese word "hong" means both red and vast. So, it could be said that red bat brings vast amount of happiness to your life.