It's a polite greeting used by students to address their teacher.
Here's a breakdown:
* 老师 (laoshi): Teacher
* 好 (hao): Good
The specific translation of "hao" will depend on the time of day.
Here are some other ways to greet your teacher in Chinese:
* 老师您好 (laoshi nin hao): A more formal and polite greeting.
* 老师早 (laoshi zao): Good morning teacher.
* 老师下午好 (laoshi xiawu hao): Good afternoon teacher.
* 老师晚上好 (laoshi wanshang hao): Good evening teacher.