To explicate is to explain or interpret something, maybe putting it in plain terms to make it more comprehensible for others. It might help to remember that it begins with "ex-," like the word explain, which is similar in meaning.
The verb explicate comes from the Latin explicāre, which means "to unfold or unravel." This is a good description of a word that means to explain something to make it clearer and more easily understandable. Think of a puzzle or mystery: when you solve it, you sometimes have to explicate how you arrived at the solution, telling how you used the clues given to find the answer.