What is the literal meaning and figurative meaning of the quote "These paper boats of mine are meant to dance on the ripples of hours, and not reach any destination"?

Literally, Tagore is here describing a visual image of paper boats "dancing," or bobbing around, on "the ripples of hours," presumably for a considerable period of time, without traveling towards any specific destination—rather, he portrays a body of placid water without any obvious current or direction, upon which the boats can bob without interference. Of course, eventually paper boats will disintegrate, but in this circumstance, they will do so in their own time, rather than due to any external accelerant other than the presence of the water itself.
Figuratively, Tagore is talking about thoughts or musings, here represented by the "paper boats." Because they are only paper boats, they will not last forever. However, because there is no particular destination in mind, there is no need for the thinker to do anything other than allow these "paper" thoughts to bob in the "ripples" of his mind for "hours." Tagore is metaphorically describing a languid reverie, a state of meditation in which thoughts can be turned over gently, to no particular end or purpose, until they lose themselves in the ebb and flow of the mind, to be replaced by others.