This song is rather short and contains lots of repeated phrases, most of which are pretty self-explanatory, but one particularly important line is "and when our children tell our story/They'll tell the story of tonight". The part about the children isn't necessarily important, but just the fact that they all want a legacy.
In the first half of the musical, Hamilton often talks about wanting to die on the battlefield and being remembered as a martyr, and in the second half, he frantically works to make the country a better place for the future generation, so they can remember his legacy. To Hamilton, having a great legacy is sometimes even more important to him than his own family (foreshadowing several very important scenes later on), and is also the main motivator behind his frantic work drive.
This song marks the start of a revolutionary spark in the characters in Hamilton, with lines such as "tomorrow they'll be more of us" and "they'll tell the story of tonight" to show that this was when they decided to take a stand against Britain's suppression of their rights.