I am POSITIVE they understand LOVE, though. When Yoda is laying down on the bed, and I walk up close to him, he always just goes flat on his back to get some hugs and kisses. He just waits for it!
I always say that they CAN talk, just we're not smart enough to understand them fully. Though I'm getting a bit better, I can understand when he wants to pee or play! That's a start at least... heheh