refers to the freedom to control your own computing. Because it empowers the user to work, study and communicate, free software is important for anyone.
Free software is relevant
just as free speech is. Software is run everywhere in our society today, governing most of what we can read and do. Unless the user has some fundamental freedoms over it, she/he has no knowledge or authority over what is happening inside it.
Free software is enabled
by the availability of source code, the "recipe" for the software. You should always be able to access and inspect this source code.
It does not matter if you do not have the knowledge or time to read and modify code: what matters is your freedom to do so, including the ability to have someone do it for you.
Free software can be copied
at no cost. You may pay, however, for it to be written, adapted and updated – this is how free software companies generate revenue.
You may always use free software for any purpose, including commercial; on the condition that it remains free if you redistribute it. You can think of it as "mathematics".