"Good mood" in English can be translated as "good mood" or "good spirits." The phrase comes from the idea of being in a positive state of mind, feeling happy and cheerful. Here are some example sentences in English and their translations in Chinese:

I'm in a good mood today. 我今天心情很好。

She always has a good mood, no matter what happens. 无论发生什么事，她总是心情愉快。

His good mood is contagious and always makes everyone around him feel happy. 他的好心情很传染性，总是使周围的每个人都感到快乐。