"happy" and "joyful" are both commonly used to express the idea of being happy and joyful in Engpsh.
"happy" 来源于中古英语"hap"或"hapness"，含义是"幸运，适意"。
"joyful" 来源于中古英语 "giōful"，含义是"高兴的，欢乐的"。
例句:
She was happy to see her friends again. (她很高兴再次见到她的朋友)
The joyful children were playing in the park. (高兴的孩子们在公园里玩)