Space is infinitely divisable, but theoretically the smallest length that it's possible to know anything about is called the
Planck Length. Talking about lengths smaller than this is meaningless.
I think you're asking about
Zeno's Paradoxes of motion. These paradoxes are very tricky to completely solve to satisfaction today. Something to think about is the sum of an infinite but decreasing series (for example 1/2+1/4+1/8+1/16+...).