If something is explicable, you can explain it. It is not a mystery once you look at the reasons. His fear is explicable after the accident. The word is rather formal. Though actually, English speakers use the opposite more: inexplicable, for the thing you cannot explain. When they do use explicable, a reason often sits in the same breath: perfectly explicable, given what happened. It does not mean the thing is small or easy — only that a clear reason exists.