"Turn on the computer" is how you would say "打开电脑" in Engpsh.

The phrasing "turn on" is commonly used to describe the act of starting a machine or device that has a switch, button, or other mechanism to activate it.

Here are some example sentences:

Can you turn on the computer so I can check my email?
I always forget to turn on the computer before I start working.
He turned on the computer and waited for it to load.

中文翻译:

你能帮我打开电脑吗，我想查看一下邮件。
我总是忘记在开始工作之前打开电脑。
他打开了电脑，等它加载。