Fundamental investing is about looking at everything that might impact the value of a company.
From looking at the balance sheets, the income statements, and the cash flow statements to get a picture of assets and liabilities, earnings, and how the company's cash situation is, to looking at the macro and regulatory environment, and also the company management, governance, product, business lines and all of its competitors.
All of that is input into a model that the investor will use to derive the intrinsic value of a company.
Then they'll look at the share price. If the share price is below what's deemed to be the intrinsic value, they'll say the company is undervalued and could be due a rise in price, however, if the company share price is above the intrinsic value then maybe it's due for a fall.