It's a statement from an optimization paper, where we have a random variable $X$ taking up values $\in \Omega_X = [0,7]$ and a decision variable $y \in \mathbb{R}^d$ , and a function $f: \Omega_X \times \mathbb{R}^d \rightarrow \mathbb{R}$.
We are interested in finding
$$ y^{*} \in \text{argmin}_y \mathbb{E}[f(X,y)]$$
We will be using a classical optimization routine to find the optimal value $y^{*}$. The value of $y$ is handled as parameter of the function $f(X,y) = f_y(X)$ .
What does it mean? Since my function is $$ f(X,y) = (y-X)c$$ where $c=0.05$
How does it changes my function?