I have a DataFrame looking like this:
amount price
age
A 40929 4066443
B 93904 9611272
C 188349 19360005
D 248438 24335536
E
As mentioned by InLaw you should use secondary_y = 'amount'
To add to his answer here is how to set the ylabels for the two axis:
df.plot.bar(figsize=(15,5), secondary_y= 'amount')
ax1, ax2 = plt.gcf().get_axes() # gets the current figure and then the axes
ax1.set_ylabel('price')
ax2.set_ylabel('amount')