Filename as column where constant value column has a names of the files

Hello, I need to process 195 xls. files. Each file has the name of the week. I need to insert constant value column based on the name of the file. Need to this for each file and concatenate them.

I have got this list files:

And to get this for each file based on the file name:

I quite lost how to do it 😐 😐