Yes, out of their wages.

Right now, they spend around 700Euro on me every month, whether it's German lessons (believe it or not, the last couple of months, they've been paying 200Euro for a Goethe Institut intensive course), and other monthly fees. We made the count, and it basically amounts to 700Euro per month, that's why, once I'm gone, since they won't be using this money anymore, it will be sent to me, in order to sustain myself economically in Germany.

I hope now it's a bit clearer.

I also understand that the amount one spends each month while in Germany varies a lot, depending on the city. I've read that München for example is a lot more expensive than, say, Heidelberg.