[The below can be done in an excel file / google sheets file or CSV file]
This is pretty easy to do.
Open your CSV file of list of words.
All of them should be in column A.
Press CTRL & F.
Then when the "Find" box pops up, click the replace tab.
Put a "-" (no quotes) in the "Find What" box, and a space in the "Replace With" box.
Then click on "Replace All" and all the hyphens will be replaced with a space.
That is it!