If that's what it takes....means that to achieve a difficult task and you are almost there, you have to dig a little deeper or work a little harder to get there. Let's say you are writing a practice test for English and you have 80% but you want 90% and your teacher says you will have to study and extra hour everyday for a month. You agree and say, "if that's what it takes". I hope that helps you understand.

"if that is what it takes" simply means " if that is what needed to be done ( to achieve something ). If I have to starve in order my children don't , I will do that if that's what it takes . If filling a complaint will stop my boss from bullying me , I will do it if that is what it takes to stop him from continuing bullying me. I will train everyday if that is what it takes for me to be a champion. I will even kill for her , if that is what it takes to win her love Employee : if that's what it takes ( then I will do it ) >This is the complete sentence if he agrees with you. > If that is what needed to be done ( to stop your boss bullying you ) , then I will do it Employee : if that's what it takes ...> His reply is unfinished and hanging , thereby indicating his uncertainty about whether what you suggested doing will really solve things .