"Five thirty" in Engpsh means "5:30" which is a way of expressing the time on a 24-hour clock. The "five" refers to the hour and the "thirty" refers to the number of minutes past the hour.
This way of expressing time is commonly used in Engpsh-speaking countries, such as the United States, United Kingdom, and Austrapa, among others.
Here are some Engpsh examples and their Chinese translations:
"What time is it?" "It's five thirty." (什么时候？ 5点半。)
"I'll meet you at five thirty." (我5点半和你会面。)
"Can you be ready by five thirty?" (你能在5点半准备好吗？)