The adverb precisely describes something done with complete accuracy or perfection. When you speak precisely, you pronounce each word completely and clearly — and you say exactly what you mean.
Something that's done precisely is done with great care, the way you'd set the table according to your grandmother's demands, precisely following her instructions about where knives and forks should go. You can also use precisely to tell about an exact time, like meeting a friend under the big clock at precisely 12:30. On its own, precisely can substitute for yes or exactly.