First of all, in describing this, you need to give it some context. You should say that this is Vespucci's claim to have reached the continent of South America before Columbus ever did. You should say that it is not clear to historians whether his account is true. This letter and others are the only real evidence of the voyage and so it is not at all certain that the voyage ever occurred.
If you are comparing this account to that of Columbus (that you asked about before) you might note the differences in the tone of the two accounts. Vespucci's account is much more focused on the nature of the people and places that he supposedly encountered. There is very little description of the voyage. The vast majority of the letter is concerned with describing the people and their ways as well as the flora and fauna of the places he says they saw.