Explain the symbolism of "The Road Not Taken" by Robert Frost. What is the moral of this poem?

The poem "The Road Not Taken " by Robert Frost is symbolic to its core. It provides a deep insight into the process of decision making. The two roads diverging in the forest are symbolic of life's choices and portrays the life's journey itself.
Life requires choices to be made and making choices can be very challenging and difficult. But one has to make a choice as making difficult choices is a part and parcel of life. The speaker in the poem made his choice after a careful consideration. He took the road that has been travelled less thus suggesting his uniqueness of choice. His choice of "less travelled road " symbolises his independent bent of mind.
Similarly, one should weigh up the options and reason out the consequences before making a choice. Once we make a choice, we cannot go back but have to face the consequences whatever it may be. It is only in future, some years hence, one can know the difference his choice had brought to his life.

I'd suggest that the symbolism of the two forest paths is ultimately about choice. Within the poem, a traveler is described as walking through a wood when the road diverges into two paths, each of which stretch on out of sight.
This entire poem hinges around the image of the two roads, where the traveler must choose between them within this singular point in time. As Frost writes in the third stanza, the traveler will, in all likelihood, never return to this place. Even so, in the very next stanza, the same traveler expects that they'll still be thinking upon this moment years into the future:

I shall be telling this with a sigh / Somewhere ages and ages hence: / Two roads diverged in a wood, and I — / I took the one less traveled by, / And that has made all the difference.

On the literal level, the traveler is walking along a road when the road splits and must choose between those two paths. On the symbolic level, it seems as though this divide refers to the choices one must make through life, whether major or trivial, and the necessity of making those choices. At the same time, the poem expresses the ways in which these past choices will still linger on long afterwards via regrets and second guessing. Everyone makes choices in their lives, and much like the traveler in the wood, they can only make them once.