"A happy day" in English. It comes from the English word "happy," which means feeling or showing pleasure or contentment. Here are some examples:

"Today was a happy day because I spent time with my friends."

"I had a great time at the party and it was a happy day for me."

"The sun was shining and I felt so happy. It was a happy day."

In Chinese, "愉快的一天" is a direct translation of "a happy day" and can be used in similar contexts. Here are some examples:

"今天是一个愉快的一天，因为我和我的朋友们在一起。"

"我在派对上玩得很开心，这是一个愉快的一天。"

"太阳正好地晒在我身上，我感觉很开心。这是一个愉快的一天。"