It's a quote from Janis Joplin
http://www.bluesforpeace.com/lyrics/bobby-mcgee.htm
The deep answer:
"Freedom" is a relative statement. Just philosophising about the word freedom us such is a bit pointless. If we want to be harsh about it none of us is free because we're all locked in a trajectory away from the Big Bang. Anybody saying they're free is always talking about it simplified. If it isn't explained what they mean, the term is worthless. We always need to state, free from what or free to do what. It can also be a goal, to increase various specific freedoms. But freedom by itself is just a pretty word.
We're all painfully aware that even in the most egalitarian democracy we're still pretty fucking far from free. Democracy if anything is just an endless list of compromises. Compromising is another word for not-being-free.
Every time I see the term I tend to get nervous because it's probably the most abused term in political propaganda there is. If any politician in Sweden would use it, I'd vote for the opposing party out of principal. In politics it's without exception accompanied by an endless stream of platitudes, full on bullshit and all out lies. It's in the same bag as "justice" and "equality". They're all relative and are worthless standing alone.
But it's a very poetically powerful word. I get this image in my head of a butterfly breaking free from its cocoon. It's a wonderful feeling. But freedom is nothing concrete we can put a finger on. It's all feeling. We're always constrained by something.
How about this definition: It's that feeling we have after breaking out of one prison, and before we understand the nature of the bigger prison we broke out into.