There are two fields that you'll want to use:

text: the text of the bill which'll be the input to the model.
summary: a condensed version of text which'll be the model target.

Preprocess
The next step is to load a T5 tokenizer to process text and summary:

from transformers import AutoTokenizer
checkpoint = "google-t5/t5-small"
tokenizer = AutoTokenizer.from_pretrained(checkpoint)

The preprocessing function you want to create needs to: