there's a similar question here, just use ax.text
and adjust the x and y positioning according to your bar value and bar enumeration, for example:
import pandas as pd
df = pd.DataFrame({'value1':[10, 30, 20],'value2':[20,50,10]})
ax = df.plot.barh(stacked = True);
print(df)
for rowNum,row in df.iterrows():
xpos = 0
for val in row:
xpos += val
ax.text(xpos + 1, rowNum-0.05, str(val), color='black')
xpos = 0
display(ax)