"Our school has 1200 people" 英文表达为 "Our school has a population of 1200 people"。

这里的 "population" 指的是学校的人数。这个词来源于拉丁语 "populus"，意思是 "人民"或 "人口"。

例句：

Our school has a population of 1200 people, which is a good size for a community college.
The population of our school has been growing steadily in recent years.
According to the latest census, the population of our school is 1200 people.

中文翻译：

我们学校有1200人，这对于一所社区大学来说是一个很好的规模。
近年来我们学校的人数一直在稳步增长。
根据最新的人口普查，我们学校的人口为1200人。