Linux-libre is a GNU package that is maintained from modified versions of the Linux kernel. The aim of the project is to remove any software that does not include its source code, has its source code obfuscated or released under proprietary licenses. The parts that have no source code are called binary blobs and are generally proprietary firmware which, while generally redistributable, generally do not give the user the freedom to modify or study them.
These details are provided for information only. No information here is legal advice and should not be used as such.