Nu ABO is a play on words meaning "New Blood Type": A, B and O are blood types, and if the letters are said in succession, it sounds like "ye-bbi-oh" ("예삐오"). The title is supposed to represent the fact that f(x) is a new group bringing their new talents, implying that they are the "new blood" to the music industry.[original research?]
It charted #1 online on Monkey3, Dosirak and Bugs, while it reached #2 on Melon. In the Philippines, it debuted on the #20 spot on the MYX International Top 20 chart and was the group's first single to debut at the said chart.