This is the 325th most frequent German word.
kleine
"Small" or "little."
In this sentence, 'kleines' is the neuter singular nominative form of 'klein', agreeing with the neuter noun 'Haus'.
Dies ist ein kleines Haus.
This is a small house.
In this example, 'kleine' is the feminine singular accusative form of 'klein', matching with the feminine noun 'Blume' in the accusative case.
Ich sehe eine kleine Blume.
I see a tiny flower.
Here, 'kleine' is the masculine singular nominative form of 'klein', modifying the masculine noun 'Hund'.