What items will the accountant need to create a 12-month Income Statement? What are the primary distinctions between a Profit & Loss Statement and Balance Sheet?

In 2018, Hamid took an early retirement after many years at the VP-level in a multinational retail banking services firm. In early 2019, he did his due diligence and completed a competitive analysis and discovered a niche market in the diversity and inclusion training space. Hamid started a consulting business offering diversity and inclusion coaching to retail banks and financial institutions. Since then he has been laser focused on building his client base and was able to achieve and sustain monthly profits since month 8.
As part of the annual 2019 tax reporting process, Hamid’s accountant is asking for receipts/invoices, and any other items which track the incoming and outgoing of cash and other business assets.
Questions
What items will the accountant need to create a 12-month Income Statement?
What are the primary distinctions between a Profit & Loss Statement and Balance Sheet?