The cash flow statement summarizesa firm's revenuesand expenses for a period of time

No, that's not entirely correct. The statement you're referring to is more accurately describing an income statement, not a cash flow statement.

An income statement summarizes a firm's revenues and expenses over a specific period of time to show the company's net income or net loss.

On the other hand, a cash flow statement summarizes the amount of cash and cash equivalents entering and leaving a company. It measures how well a company manages its cash position, meaning how well the company generates cash to pay its debt obligations and fund its operating expenses. The cash flow statement is broken down into three parts: operating activities, investing activities, and financing activities.