Subject + 很 + 开心 / Verb + 得 + 很 + 开心
开心 (kāixīn) is an adjective meaning "happy," "joyful," or "delighted." It combines 开 (to open) and 心 (heart), literally meaning "open-hearted." It is commonly used to describe a cheerful emotional state and is often paired with 很 (very) for emphasis or used in the structure 很开心 as a predicate.
收到礼物她特别开心。
Shōudào lǐwù tā tèbié kāixīn.
She was especially happy to receive the gift.
今天和朋友聚会,大家都很开心。
Jīntiān hé péngyou jùhuì, dàjiā dōu hěn kāixīn.
I got together with friends today, and everyone was very happy.
孩子们在游乐场玩得很开心。
Háizimen zài yóulèchǎng wán de hěn kāixīn.
The children had a great time at the amusement park.