This is what happen when non-developers like me copy and paste working code rather than actually understanding it!
Yes, the key idea is,that the variable name in itself doesn't convey any information. So, you have to do things like "type(plt)" to learn which type the object is, where the variable "plt" is pointing to.
Then, you would have noticed that the return value of the pandas plot is an Axis object.
PS: In case you are lost and need the current figure or axis of matplotlib: it's plt.gcf() and plt.gca() if plt is this pyplot api you are canonically importing in the beginning.