What's the meaning of the number before the progress bar when tensorflow is training
10 and 49 corresponds to the number of batches which your dataset has been divided into in each epoch. 
For example, in your train dataset, there are totally 10000 images and your batch size is 64, then there will be totally math.ceil(10000/64) = 157 batches possible in each epoch.
Could anyone tell me what's the meaning of  '10' and '49' in the following log of tensorflow?
Much Thanks
INFO:tensorflow:Started compiling
INFO:tensorflow:Finished compiling. Time elapsed: 5.899410247802734 secs
10/10 [==============================] - 23s 2s/step - loss: 2.6726 - acc: 0.1459
49/49 [==============================] - 108s 2s/step - loss: 2.3035 - acc: 0.2845 - val_loss: 2.6726 - val_acc: 0.1459
Epoch 2/100
10/10 [==============================] - 1s 133ms/step - loss: 2.8799 - acc: 0.1693
49/49 [==============================] - 17s 337ms/step - loss: 1.9664 - acc: 0.4042 - val_loss: 2.8799 - val_acc: 0.1693