This is a line from the song "L'internationale", a song that is widely considered an anthem for those on the left around the world. It was originally sang in the Paris Commune as the workers there fought to organise and separate themselves from the wealthy, owner class of that society. It is currently being sung again in the protests and civil unrest happening in Paris today after Macron and the French Senate have push through an increase to the retirement age.
The above rendition of the song is sung in many languages by people of many different backgrounds. Because the left rejects nationalism and racism, being on the left puts one with solidarity with others all around the world in a way that being on the right does not. People the world all over are oppressed in the same ways, for the same reasons, by the same forces.
L'internationale is the anthesis to a national anthem. An anthem of the oppressed all over the world.
On to the quote itself, I view it as a nice summation of how the left views freedom. It's privilege unless extended to all. What kind of person can truly enjoy the freedom that they have knowing that their fellow beings are suffering in chains? It seems that for those who have the freedom, it should be used to change our state of affairs. Furthermore, what is freedom without the necessities in life: a secure stream of food, water, shelter that we can take for granted? It's either freedom to starve or freedom to remain at the mercy of those who can provide that which you need to live.
There's a lot more meaning and history to the song. I recommend that you watch the video The Internationale Explained by Azure Scapegoat to learn more (it's ~12 minutes).