Large rotating magnetocaloric effect (MCE) has been recently observed in HoMn2O5 single crystals due to the strong magnetocrystalline anisotropy making a significant step towards efficient magnetic refrigeration systems. We tried to explain, theoretically, the reasons behind the magnificent performance in terms of magnetocaloric effect based on DFT calculations and Monte Carlo simulations. X-ray magnetic circular dichroism (XMCD) was performed in order to disentangle the magnetic contribution responsible for the MCE, as well as, the investigation of electronic and magnetic properties. The obtained results would enable the understanding of electronic and magnetic behaviors experimentally observed in HoMn2O5 single crystals and the optimization of their MCE for magnetic refrigeration application.