I will separate my business code into a script language. it would be Lua or Python. 
My question is my business code written in script file is viewable by others.
Because of script file will not compiled that is open. Anyone can see it.
How can I hide it?
I think if I use Python, it would be compiled (.pyo), but Lua looks like more suitable for me.
(For Lua)
Depends on how safe it should be. For keeping out dumb edits you can just change the extension, and configure the path to recognize it anyhow.
For keeping out people who know how to change extensions, you can ship files compiled with luac. For deciphering that you already have to put considerable effort in it.
But to be really save I guess the only way is to encrypt/sign the code, and perhaps modify the core such that it'll only run files who's signature checks out to be OK, or which can be decrypted.
Compiling script files Lua or Python