This is the 657th most frequent Danish word.
luft
"Air."
Here, 'luft' refers to the air in a general or environmental sense.
Jeg åbner vinduet for at få frisk luft.
I open the window to get fresh air.
In this context, 'luft' is used metaphorically to indicate something without substance or unrealistic.
Han har mange planer, men de er bare luft.
He has many plans, but they are just air.
Here, 'luft' describes the physical air used to inflate something.