This is the 136th most frequent Danish word.
lille
"Little" or "small."
Here, 'lille' is an adjective describing the noun 'hund', indicating its small size.
Jeg har en lille hund.
I have a small dog.
In this sentence, 'lille' is also an adjective but is now used with the intensifier 'meget' to emphasize how small the shop is.
Den butik er meget lille.
That shop is very small.
Here, 'lille' functions adjectivally to differentiate the specific book as the smaller one among others.