This is the 140th most frequent Danish word.
længe
"Længe" means "for a long time" in English.
In this sentence, 'længe' is used as an adverb to describe the duration of waiting.
Jeg har ventet længe på bussen.
I have waited a long time for the bus.
Here, 'længe' functions as an adverb as part of the expression 'Hvor længe,' which means 'how long' to ask about time.
Hvor længe skal vi blive her?
How long should we stay here?
In this case, 'længe' is again an adverb, used to emphasize the extent of the speaking duration.