Spin is the intrinsic angular momentum of an elementary particle, measured in units of the reduced Planck’s constant ħ. In quantum field theory, the spin of a particle is related to its behaviour. For example, particles with integer spin (0, 1, 2…) are called bosons, and can occupy the same quantum state at the same time. In contrast, particles with half-integer spin (1/2, 3/2, 5/2…) cannot. The known elementary constituents of matter (electron, quarks, neutrinos…) are spin 1/2 particles, whereas the particles (photon, W/Z, gluon) which mediate the known interactions (respectively electromagnetic, weak, strong) are spin 1 particles.
The Higgs boson has spin 0 (it is a so-called “scalar” boson) and positive parity as predicted by the Standard Model. It is the only elementary scalar particle to be observed in nature.