A many-body resonance emerges at the Fermi energy when an electron bath
screens the magnetic moment of a half-filled impurity level. This Kondo effect,
originally introduced to explain the abnormal resistivity behavior in bulk
magnetic alloys, has been realized in many quantum systems over the past
decades, such as quantum dots, quantum point contacts, nanowires,
single-molecule transistors, heavy-fermion lattices, down to adsorbed single
atoms. Here we describe a unique Kondo system which allows us to experimentally
resolve the spectral function consisting of impurity levels and Kondo resonance
in a large Kondo temperature range, as well as their spatial modulation. Our
experimental Kondo system, based on a discrete half-filled quantum confined
state within a MoS2 grain boundary, in conjunction with numerical
renormalization group calculations, enables us to test the predictive power of
the Anderson model which is the basis of the microscopic understanding of Kondo
physics