The general idea is that is so strong that at microscopic distances all charges get neutralized by opposite charges or by the other color charges (because three different color charges neutralize themselves, like in the proton). This happens to in electric charge, but there are a few phenomena by wich at macroscopic scales it manifest:
*Electric charges can be separated from a bunch of matter, so the matter gets charged. This can't happen with nuclear strong force, because it's so strong that the energy needed to separate one charge un-neutralizing a bunch of nuclear matter (for example, taking a quark from a proton) is enough to make a quark-antiquark pair that neutralizes the separated charge (with the antiquark) and the bunch of matter.
*Electric charges can radiate photons to infinity. Even if it's not understood how (that is the "mass gap" part of the problem "Yang-Mills existence and mass gap") it's supposed that the carriers of the strong force get massive (and not by a Higgs mechanism), and in some sense they can't get far away from the source of the radiation.
Also, we aren't really sure that it gets stronger with the distance, but it can't get weaker with distance. We only can only say that it gets weaker at shorter and shorter distances, that's called "Asymptotic Freedom". Even, at scales much smaller than the proton and the neutron, they can get weak.