Denotation means the literal meaning of a word or name. Although Paris might make you think of romance, its denotation is simply the city of an old tribe called the Parisii.
The Latin word denotare means to mark, and denotation originally meant the act of marking or the expression of something through a sign. Now we tend to use denotation in opposition to connotation, which is indirect or symbolic meaning. The denotation of rose is a particular kind of flower, while the connotation is of romantic love; the denotation of river is a body of water, while its connotation might be the unending flow of time.