We should consider that the part of the play to which you refer is found within the first Act, particularly where the stage directions begin followed by the inciting action. This is the part where most of the motifs and symbols are established as part of the atmosphere and setting of the stage. It is also in this part of Act I where we get to see Willy's actual problem, the situation with the family, and the daydreams in which Willy becomes enthralled to the point of losing his sense of reality.
This being said, the symbols that stick out the most in the stage directions are allegorical of the situation that the Lomans are going through: They are a family in the search of their American Dream. Once, the house that they are about to finish paying off would have been the sign of success that every American man of Willy Loman's age would have dreamed of. However, the setting of the house tells us that Willy's home structure resembles Willy's own backbone: It has been covered by the modern ideals that make Willy's American Dream seem antiquated.
Before us is the salesman's house. We are aware of towering, angular shapes behind it, surrounding it on all sides.[....] As more light appears we see a solid vault of apartment houses around the small, fragile-seeming home.
Similarly, we see the motif of the dreams. Not only does Willy's wish of the American Dream serves as the backbone of the play, but we also notice that dreaming is a natural-and dangerous-tendency in Willy Loman. We know this when he admits to Linda that he nearly kills someone as he drove towards the house when he let the fresh air in his car and faded away in a daydream.
If I'dve gone the other way over the white line I might've killed somebody! So I went on again -and five minutes later I'm dreaming again.
Here we see that dreaming is what has made up all of Willy's reality in this part of his life, where instead of dreaming he should be remembering. However, we know that half of his dreams are remembrances...but, are they? We, as audience members, do not know if Willy's dreams are all made of things that actually happened, or if there are also "what if's" included. This is why it is interesting to note that dreaming seems to be a primary nature in Willy's character. A dangerous nature that totally detaches him from reality.
It is in this part of the play where we know that Willy continues to work at 63 the same hours and mileage that he had done when he was a younger and more energetic salesman. According to Willy, he is:
The New England man. I am vital in New England.
This is significant because, later on, we will see that this is only one of Willy's ideas about himself: That he is "the New England man", that he "is Willy Loman and, in all, that he is a whole lot of things that he really is not. This is the same legacy he passes on to his two boys, Biff and Happy who, now in their 30's, still do not know who they really are, nor what to do with their lives.
Hence, this part of the play shows us a glimpse into the overall persona of Willy Loman and its symbols are mainly allegorical to the way that he, as a man, is falling with the passing of time and his ridiculous insistence in sticking to a dream that is all wrong.