To accentuate something is to emphasize it. If you want someone to know you’re from the American South, accentuate your accent by laying it on thick, y’all.
When you accentuate, you draw attention to something. You could wear a green shirt to accentuate your green eyes, for example. You can also accentuate words when you give them added stress. An actor might accentuate certain words in a monologue in order to emphasize the character's anger. This word traces all the way back to the Latin verb canere, "to sing."