What this means is that, if we tried to detect such particles in our current universe, those are the masses we would have to be able to detect--which means we would have to be able to run experiments that involved particles with energies of that order of magnitude. We are many orders of magnitude short of being able to do that. As I understand it, in grand unified theories, the Higgs field that is involved in electroweak symmetry breaking is not the "entire" Higgs field; it's only a piece of it. There is another piece of the Higgs field that is involved in grand unified symmetry breaking, and gives mass to the GUT bosons after that symmetry breaking event, and leaves behind what we usually call the Higgs field, the one that's involved in electroweak symmetry breaking. However, we haven't observed any of the GUT bosons, and, for the reason I gave above, we don't expect to any time soon. So we don't really have any experimental test of the GUT Higgs mechanism, whereas we do have experimental tests of the electroweak Higgs mechanism. So we don't really know for sure how the GUT bosons acquire mass, the way we know how the weak bosons acquire mass. We don't even know for sure which GUT, if any, is the right one; there are multiple possible GUT's that are consistent with what we currently know.