How to add label to QgsVectorLayer by python

my goal is to define label programmaticly for the case similar for the figure below:

But didn't find any guidance how to do so using Python.

I have a feeling it could be done using QgsLabel but didn't find any working exmaple how to do so.

Please provide me with some example how to do so; If I'm wrong with QgsLabel idea - please explain briefly the rigght approach for this. As usual some code example could be very useful...Thanks!