The Latin word capita means "head." If you're a Spanish learner, you may know the word cabeza, "head," which comes from the Latin. Several English words and expressions come from this Latin root. Here are a few examples.
per capita: This is an expression that means "per person." How do we count people? We do a head count, right?
capital: A capital city is the head city of a country.
decapitate: Literally, to "de-head," though we might more naturally say "behead."
capitulate: This means "surrender"; I tend to think of the notion of bowing one's head in defeat, but the actual etymology refers to putting things in sections (i.e., under headings). See here.
recapitulate: We use this word when we're talking about re-covering, perhaps in summary form, the topics we've just covered in a discussion. When we recapitulate, we're "taking it again from the top," i.e., from the head.