Valuation of securities

Could someone explain me the valuation of securities?

Valuation of securities are include dividend valuation model (constant growth and remain constant)/ Gordon growth model and valuation of debt (irredeemable preference shares and redeemable loan stock).

A general market model for the valuation of securities on the basis of the discounted value of future cash flows. Is it the discounted value of future cash flows is future value of a share?

What is the purpose for using these model?

Thanks.