Yes, we should talk about this. Like seriously, it has become very common, even non-muslims use the phrase. Very nice though, but the root of it isn't know to most of us.
The phrase means "If God Wills and it originated from a Quranic command which obligates Muslims to use it when speaking of future events.
Reason behind this, is to let us know that no matter what ever our plan might be. The success of such plan or plans depends on the Will of Almighty Allah.
For instances: I will do what I can to finish the painting tomorrow. ❎
And
I will do what I can to finish the painting tomorrow, In Sha Allah. 😊☑️
Thereby leaving your future into Allah's Mighty Hands. Which is safer, because in case of any casualty or inability to meet up with your agreements, Allah's Will has come to pass.
We should make this part of our daily phrases and stay clear off making Promises. Never forget that :" Man Proposes, God Disposes".
Good one writer. You done a great job here. Not everyone knows the meaning but now they do.