Tldr: it’s just a property of concentric circles (and it’s talking about average distance, not the closest passing).
I’ve made a diagram using online Paint on my phone, which I think you’ll agree is nothing short of perfect.
Basically you’re the blue dot (could represent any planet), and the purple is the sun (the middle of the concentric circles). The brown line represents the distance you are from it. The red lines represent orbits closer to it than you. As you can see, the further out the orbit, the more of it lies beyond the brown line. Ergo the closer to the middle the orbit is, the closer it is to you (on average).