The kind argument

df = pd.DataFrame({
    "city": ["Nairobi", "Mombasa", "Kisumu", "Nakuru", "Eldoret"],
    "units": [21, 15, 15, 18, 12],
    "shillings": [2100, 1500, 1480, 1750, 1190],
})
for k in ["bar", "barh", "line"]:
    df.plot(x="city", y="units", kind=k, title=k)
    plt.show()

df = pd.DataFrame({
    "units": [12, 7, 9, 4, 11, 3, 14, 8],
    "shillings": [1260, 1540, 945, 880, 1155, 660, 1470, 1760],
    "city": ["Nairobi", "Nairobi", "Mombasa", "Mombasa", "Kisumu", "Kisumu", "Nakuru", "Eldoret"],
})
df.plot(x="units", y="shillings", kind="scatter", title="scatter")
plt.show()