The book was originally dedicated to Giuliano de Medici, who took Florence when the Medicis returned in 1512. Unfortunately, Giuliano died just four years later, so Machiavelli decided to switch it up. As you've probably noticed already, the book ended up being dedicated to Lorenzo di Piero de' Medici, Giuliano's nephew.
In the last paragraph Machiavelli pleads for mercy, and frankly it's a bit hard to read. He explains how much being in exile stinks and basically begs to be brought back into politics.
His dedication is pretty normal. Around this time, everyone used dedications like this when writing to someone of high rank. The template called for saying how awful you are but how amazing the person you were writing to was, and Machiavelli follows this to a tee. The dedication is so traditional that we can even tell what text it's based on (Isocrates' address to Nicocles).
Machiavelli also lets us know from the beginning that this isn't going to be a fancy pants book. No frou-frou. No complicated words. Just knowledge comin' at ya.
Even though today we mainly look at The Prince as an important work of political theory and philosophy, the dedication helps remind us what it originally was: just a little present from Machiavelli to Lorenzo. It wasn't meant for our prying, commoner eyes or for smarty pants scholars; it was meant for the guys who were going to rule.
Or so he says.