Anyway...
Q: What is the first effect when a spring is added to the stick?
A: It centered the stick.
How freaking easy can it get?
Now we know you do not know the answers to a dozen basic aerodynamics questions, we moved onto Flight Controls, my first specialty.
Q: Since fly-by-wire eliminate the mechanical connections between the stick and the hydraulics, what is the spring used for?
You
MUST be able to search for this. If you have even just one semester of aerodynamics, that should be sufficient to give you enough keywords to search for this answer.