I'll take a stab at this. I think what this means is that, "I really value you as a person and I know I'm not ready to be everything you need right now. As opposed to allowing you to take a chance on me that I won't be able to deliver on, I'd rather we just remain friends so that the expectation level and disappointment isn't an issue."
Effectively, the person is just letting you know that while they do like you and have an interest in you, they're being honest about where they are in their life right now and aren't willing to be the person to screw you over emotionally and romantically.
That's really kind of nice actually.
Now, it's on you to decide how to proceed though it seems like your options are pretty slim. So, just thank them for being honest, and find somebody else to love.
I agree. I think it means that he is trying to better himself as a person (whether financially, career-wise, etc.) and until he can make sure that he succeeds in securing a future himself, then he'll know he can provide for and support you.