How does the kinetic theory of gases explain heat?
Through the equation
For other relations for enthalpy, H, refer http://socratic.org/questions/what-is-the-formula-used-to-calculate-enthalpy#183545
Collisions of gaseous particles involves particles moving with a certain kinetic energy. And not to mention the fact that molecules possess translational, rotational, and vibrational energy. All these energies that are combined together to give enthalpy, H (This is only true for constant pressure system. For constant temperature system, internal energy, U, is the relevant variable.).
Enthalpy, H, is the relevant variable for heat because it relates to the change of temperature of the system.