Follow the link above to the website of the Virginia Museum of Fine Arts. They have a feature which allows you to magnify the details on the bowl. The bowl, incidentally, was made at the famous Jingdezhen kilns in Jiangxi province.
The character for bat, 蝠, is pronounced “fú.” The character for luck or fortune, 福, is also prounced “fú.” When five bats are depicted, as on the bowl above, they symbolize the “five fortunes” of good luck, prosperity, wealth, happiness, and longevity. The red color is a further pun between the word for red (红, hóng) and the word for vast (宏, also hóng): a red bat means “vast fortune.”