While watching captain America in English, I heard Chris Evans saying " If that's what it takes " What exactly does the sentence mean ?
I haven't seen the movie so I don't know the context. But in general, "that's what it takes" means that these are the things required to complete this job or reach this goal.
A very literal example would be, "What does it take to replace spark plugs in my car?" To which someone might reply, "You need a set of socket wrenches, a spark plug puller, and of course the new spark plugs."
The phrase is often used for less concrete requirements. Like, "John really has what it takes to be a champion athlete", meaning, he has physical strength, a willingness to practice long and hard, etc.