We can use distribution property to multiply the polynomial by the monomial.
$$ \begin{aligned} \color{blue}{2a} \cdot \left( 5a^2+8a+8 \right) &= \color{blue}{2a} \cdot 5a^2 + \color{blue}{2a} \cdot 8a + \color{blue}{2a} \cdot 8 = \\ &= 10a^3+16a^2+16a \end{aligned} $$