Please explain me the following lines :

Two roads diverged in a yellow wood ,
And sorrow I could not travel both
And be one traveller , long I stood
And looked down one as far as I could
To where it bent in the undergrowth ;

This poem is an exposition on the choices we make in life, the opportunities that we do take up and the countless others that we let go of to concentrate on the choices that we have made. The poem begins with two diverging roads in a yellow wood and the poet's realization that it is impossible to follow both. Both the roads have not been taken by him before and standing at the crossroads, he is unaware of which road leads to where, so both seem like fair enough choices to him. The one that he finally took was grassy and wanted wear, it is evident that he hadn't been trodden upon by other feet. But the poet says that this could be his illusion because the grass proverbially seems greener on the other side. So, what he wants to convey is that one should stick to the choices that one has made without calculating the opportunity cost of not taking the other one. Second guessing and self-doubt are part and parcel of the human disposition in general, so we will always wonder about the 'what ifs' and the 'if only'. As the poet embarks on his journey, he says to himself that he might come to the second road another day knowing fully that it is not possible. It is just to make himself be less scared about the daunting prospect of making a final decision. As he reflects upon that grassy road, the one less traveled by some years down the line, he realizes that it has made all the difference. He made the choice on his own, listening to himself and no matter what hardships he had to face, he seems to have no regrets. This is what the poem urges us to do, to make those choices even if we are not confident about just on the basis of what our heart tells us to do. We have to take chances, some work out and some don't but if we never try things out, we will never know which would have worked for us.