可樂 is a loanword for cola (the Mandarin pronunciation kě lè is pretty close), but in a punny way it also means entertaining.
可 by itself is able to (but is generally used in 可以 for that meaning).
樂 by itself is music (but more generally used in 音樂 for that meaning). So you can remember 可樂 as can music.
Cola soft drink. You would use this word when ordering a Coke (but there's another word specifically for Pepsi).
Ordering
杯 is cup (or mug or glass) and is the measure word for water (and other drinks), and 一 is one, so to order a glass of cola, ask for 一杯可樂 (yāt būi hó lohk in Cantonese, yī bēi kě lè in Mandarin), one cup of cola.