yikes i was waiting for somebody much more advanced in Buddhist studies to answer this but well based on my own limited knowledge..please forgive me if it's very poor...
Enlightment or Nibbanna mean Cessation..you know like you just "stop" or "end"..."cease".You know like a candle when you extinguish the flame.That sort of ending.just stop.
If people do attain enligthement i think they won't tell you this.i'm not sure why myself.
I think you can try to imagine enlightment in an emotional,spiritual or intellectual level.You can imagine it as peace or bliss.You can imagine how it would feel like... how it would be ..you can think about it.
But when you Do reach the state of enlightment it is none of these things.Enlightment just can't be understood through words,concepts,perceptions..or descriptions.That's the thing it can't be "understood"..one must Experience it for oneself.
hope this helps.