New and have a Q about protected files

[buttercup]

First of all...Hello everyone. I am really getting fustrated and I need some help please. I downloaded Switch, since my husband brought home a bunch of music on his flash drive from the computer at his job. They are WMA files...there's a few that I was able to convert to mp3's but the majority of the WMA files say, when I hit the convert button is "file is protected my DRM (diital rights management). What does this mean and how can I get these WMA's unprotected, if that's the correct wording?? I really just want to convert them to mp3's. If anyone can help me, I'd really appreciate it. Thanks in advance.