matplotlib strings as labels on x axis

Use the xticks command.

import matplotlib.pyplot as plt

t11 = ['00', '01', '02', '03', '04', '05', '10', '11', '12', '13', '14', '15',
       '20', '21', '22', '23', '24', '25', '30', '31', '32', '33', '34', '35',
       '40', '41', '42', '43', '44', '45', '50', '51', '52', '53', '54', '55']

t12 = [173, 135, 141, 148, 140, 149, 152, 178, 135, 96, 109, 164, 137, 152,
       172, 149, 93, 78, 116, 81, 149, 202, 172, 99, 134, 85, 104, 172, 177,
       150, 130, 131, 111, 99, 143, 194]


plt.bar(range(len(t12)), t12, align='center')
plt.xticks(range(len(t11)), t11, size='small')
plt.show()

In matplotlib lingo, you are looking for a way to set custom ticks.

It seems you cannot achieve this with the pyplot.hist shortcut. You will need to build your image step by step instead. There is already an answer here on Stack Overflow to question which is very similar to yours and should get you started: Matplotlib - label each bin

For the object oriented API of matplotlib one can plot custom text on the x-ticks of an axis with following code:

x = np.arange(2,10,2)
y = x.copy()
x_ticks_labels = ['jan','feb','mar','apr']

fig, ax = plt.subplots(1,1) 
ax.plot(x,y)

# Set number of ticks for x-axis
ax.set_xticks(x)
# Set ticks labels for x-axis
ax.set_xticklabels(x_ticks_labels, rotation='vertical', fontsize=18)