To understand why, start with this common construction with the word "make":
Make my hair shiny.
"Make object complement" means to cause object to have the property named by complement. The subject is the person or thing that causes object to acquire that property:
This shampoo will make your hair shiny.
Since this is in the future tense, it means that the shampoo will cause your hair to become shiny.
You can use the same construction in the present tense to explain why an object has some property:
"What makes your hair so shiny?"
"This shampoo makes it shiny."
If your hair wasn't already shiny, then the question wouldn't make sense. "What makes object complement?" asks what is the cause of the object's already having the property named by the complement.
"What makes Amir good at speaking English?"
"I don't know for sure. Maybe it's because he memorizes a lot of nursery rhymes."
The object is Amir and the complement is good at speaking English.
Seriously, Amir is good at speaking English because he has practiced a lot. :)
You can also use the same construction with "make" to ask how an object that doesn't have the complement yet could acquire it. You just add a modal verb to "make", like this:
What will make my hair shiny?
What would make my hair shiny?
What can make my hair shiny?
What could make my hair shiny?
What might make my hair shiny?
These all mean approximately the same thing, with only subtle differences. The versions with "would", "could", and "might" are ambiguous: they can also ask what causes the hair's shininess right now (instead of asking how the hair could become shiny). To be fully clear, you can add another verb to reinforce your intended meaning:
What would make Amir become good at speaking English?
What could make Amir get good at speaking English?
What will make Amir get good at speaking English?
...and many other variations.
However, note that the "make" construction suggests a simple, rather forceful kind of causation, like making hair shiny or making your car run faster. The wording above suggests that maybe you are looking for some kind of threat or incentive to make Amir practice more. If you want to ask for a method or an action, "how" fits your meaning better:
How did Amir get good at speaking English? [This assumes that Amir is already good at speaking English.]
How could Amir get good at speaking English? [This assumes that Amir is not currently good at speaking English.]