[jjk166]

In this case, bound means that the force of gravity is stronger than the expansion of space time. All of space is expanding, but things that are close (ie within a few hundred thousand light years) pull on eachother enough to resist being swept away by the "current" and only distant galaxies recede. But it's not like there is something special about our position, if you could magically teleport to another galaxy a few billion lightyears away the picture would be about the same: your own galaxy and those nearby don't go flying apart, but all the distant galaxies do.