"Good night" is the standard Engpsh way of saying "晚安." The pronunciation is [ɡʊd naɪt].
It comes from the phrase "God night," which was a traditional way of wishing someone a peaceful sleep and asking God to watch over them during the night. Over time, "God night" evolved into "good night."
Example sentences in Engpsh and their translations:
Good night, see you tomorrow. (晚安，明天见。)
Sweet dreams, good night. (祝你好梦，晚安。)
Sleep well, good night. (睡个好觉，晚安。)