He means that if you send your RADS to the wallet and you unlock it, you will earn more RADS as a reward for contributing to the network as a node.
If you have 1000 RADS ( ≈1280$ as today's price), you will earn approximately 0,75 RADS per day, so the more you have, the more you ''stake''.
I find it very profitable at the moment, and considering this project has lots of potential, I think it's also a really good investment for the long term.