This is the 5303rd most frequent Dutch word.
klein
Small.
The word 'klein' is used here as an adjective to describe the size of the house as small.
Het is een klein huis.
It is a small house.
In this sentence, 'klein' is again an adjective, describing the problem as being minor.
Ze hebben een klein probleem gevonden.
They found a small problem.
Here, 'klein' functions as an adjective to describe someone physically being of small size or stature.