[kyllo]

어 (transliterated as either "eo" or "uh") is a vowel that I would describe as like the "u" sound in the word "fun" but with the mouth open a bit wider.

It's nothing like any of the sounds an "e" can represent in English.

Europeans tend to pronounce it "See-OOL" which is just completely wrong.

[devonkim]

It's a bit longer, always morphemic version of a schwa I believe.