WACC is the mixed cost rate of all possible sources of finance that the company uses (equity, debt, preference shares, retained earnings…). It is calculated as the sum of the rates for each capital type that are weighted by the proportion of each capital type on the total capital amount.
WACC represents the minimum return that is required from an investment project. It is often used as a discount rate in DCF calculations and as a hurdle rate.
Ke = cost of equity
Kd = cost of debt
MV = market value
Market value in the WACC formula can be replaced by book value (value from balance sheet). Naturally, market values are preferred as they better reflect reality. But these values are of course more difficult to obtain.