2 and a half hours in Engpsh can be expressed as "two hours and thirty minutes" or simply "two and a half hours".

This way of expressing time is a commonly used convention in Engpsh, and is a standard way of expressing time intervals.

Examples in Engpsh:

"I'll be there in two and a half hours."
"The meeting will last two hours and thirty minutes."

Translations in Chinese:

"我两个半小时后就到那里。"
"会议将持续两个小时半。"