Step 1 :
Factor out common factor $ \color{blue}{ y } $:
$$ 5xy^2+5xy-y^2-y = y ( 5xy+5x-y-1 ) $$Step 2 :
To factor $ 5xy+5x-y-1 $ we can use factoring by grouping.
Group $ \color{blue}{ 5xy }$ with $ \color{blue}{ 5x }$ and $ \color{red}{ -y }$ with $ \color{red}{ -1 }$ then factor each group.
$$ \begin{aligned} 5xy+5x-y-1 &= ( \color{blue}{ 5xy+5x } ) + ( \color{red}{ -y-1 }) = \\ &= \color{blue}{ 5x( y+1 )} \color{red}{ -1( y+1 ) } = \\ &= (5x-1)(y+1) \end{aligned} $$