The main purpose of the proposed legislation, known as the "One Subject at a Time Act," is to ensure that each bill passed by Congress focuses on only one topic. This aims to simplify the legislative process and make it clearer for lawmakers and the public to understand what each bill is about. By limiting bills to a single subject, the act seeks to prevent the practice of bundling unrelated issues together, which can lead to confusion and unintended consequences. Key provisions of the act include a requirement that each bill or resolution must only address one subject.