但愿吧 is a Chinese expression that roughly means "let's hope so" or "I hope so." In English, it can be translated as "I hope" or "I wish."

The origin of this expression is not clear, but it is commonly used in Chinese to express hope or desire for something to happen.

Here are some examples of how it can be used in English:

"I hope the weather will be nice tomorrow." (但愿吧，明天的天气会很好。)

"I wish I could go on a vacation." (但愿吧，我能去度假。)

"I hope we can meet again someday." (但愿吧，我们能在某天再次见面。)