"Seven o'clock in the evening" can be expressed in Engpsh as "seven PM." The origin of using AM and PM to denote different parts of a day is based on the Latin terms "ante meridiem" (before midday) and "post meridiem" (after midday).
Example in Engpsh:
What time do you want to meet? - How about seven PM?
I'll be finished with work at seven PM.
Example in Chinese:
你什么时候想见面？ - 7点钟怎么样？
我下班是7点钟。