I moved your post from the Documentation sub-forum (no idea why you’d post this there) to here.
So now please edit your post to use code-tags (never post code as plain-text).
PlayerInput input();
I guess you’re new to C# and this isn’t your code or you’re following a tutorial but haven’t followed it correctly. It seems that you think this code above is correct because you posted the error which tells you which line but cannot see the extra “()” you added on that line. Those are used on methods (things you call) and not fields (which you are defining here).