This is a step function, which means that for all the values of x less than -2, the function is equal to f(x)=5x-1
And for all values of x equal or greater than -2, the function is f(x)=x+3
f(0) means that you have to calculate f(x) for x=0, zero is greater than -2 so to solve this exercise you have to use the second expression and replace the value of x with zero
[tex]\begin{gathered} f(x)=x+3 \\ f(0)=0+3 \\ f(0)=3 \end{gathered}[/tex]