This will be helpful for You to interpret kurtogram https://www.mathworks.com/help/predmaint/ug/Rolling-Element-Bearing-Fault-Diagnosis.html
If we look on the results the most important elements are:
Kmax = 2.7083 - is maximum value or kurtosis
Optimal Window Length = 128 - this value we can use to calculate spectral
Center Frequency = 2.6703 kHz ...
[Given figures are from A new improved Kurtogram and its application to planetary gearbox degradation feature analysis, Xianglong Ni et al.]
This $k$ in the graph (and the $K$ in the Table) corresponds to an equivalent "dyadic-power", providing the number of subsequences at each level, alternating dyadic splits with filters on subbands $[0,1/4]/[1/...