While it looks like there are a lot of fields here, it is actually pretty straightforward:

sent1 and sent2: these fields show how a sentence starts, and if you put the two together, you get the startphrase field.
ending: suggests a possible ending for how a sentence can end, but only one of them is correct.
label: identifies the correct sentence ending.

Preprocess
The next step is to load a BERT tokenizer to process the sentence starts and the four possible endings: