Hi Oliver,
Your cashflow should show how cash is moving around through your business. It should show your cash inflow and outflow, combining to form your net cash flow.
The most common cash inflow would be revenue generated from customer purchases or royalties if applicable.
Some cash outflow examples are investments, purchases, and loan repayment.
Your income statement should show your net profit, found by subtracting expenses from income. Income is typically constituted of customer purchases while expenses cover things such as research and development, cost of goods sold, marketing costs, and taxes.
Good luck!