This is the 6284th most frequent Chinese word.
快樂
"Happiness" or "joy."
Here, '快樂' is used as an adjective to describe the state of feeling happy.
我希望你每天都能感到快樂。
I hope you can feel happy every day.
In this sentence, '快樂' is used as a noun referring to the concept of happiness.
小明的快樂來自於與朋友的交流。
Xiao Ming's happiness comes from interacting with friends.
Here, '快樂地' is an adverbial phrase formed with '地', describing the manner of smiling.