Add a new column to multiple .csv and populate with filename
If the position of the columns are the same across all excel file, you can iterate all the 15 excel files, locate the position of the column and replace the text directly. 
Alternatively, you can iterate all the files via read_xls (or read_csv depending on your context), reading them as dataframe and replace the necessary column name, and overwrite the file. Below is a reference syntax for your reference. 
df.rename(columns={ df.columns[1]: "your value" }, inplace = True)
I am new in python and I have a folder with 15 excel files  and I am trying to rename a specific column in each file to a standard name, for instance I have a columns named "name, and server" on different files but they entail of the same information so I need to rename them to a standard name like " server name" and I don't know how to start