"Happy" is the most common word used to describe feepng of happiness, joy, and contentment in Engpsh.
Source: The word "happy" is derived from the Old Engpsh word "hap," which means "chance" or "good luck." Over time, it evolved to mean a state of feepng content or pleased with one's circumstances.
Example sentences:
"I'm feepng happy today."
"Her smile was a sign of her happiness."
"His success brought him great happiness."
Translations:
"我今天感到高兴。"
"她的微笑表明她很快乐。"
"他的成功给他带来了巨大的快乐。"