I would like to know the meaning of the three matzot and why only the middle one is broken.
Of the three matzot on the table, why is it that the middlte matza is the one which is broken? The halakhic answer is: On Pesach three matzot are required. One for lechem o'ni (poor man's bread) and two for lechem mishna (the two loaves required on each Shabbat and Yom Tov). Since it is customary to lay one's ten fingers on the lechem mishna [as a reminder that ten mitzvot are fulfilled in the process of producing and eating bread] these matzot must be placed on the top and bottom of the pile.
He also quotes "two of many" answers "on the level of derush. I'll leave it to others two write up their favorites from that category.
There are many explanations, meanings and innuendos. Here are a few:
Avraham served the Angles-disguised-as-men three loaves when they arrived at his home. That was on Pesach.
We compare the Matzah to "poor man's bread" an a poor man always puts some away for later, hence the "break and hide" routine of the middle matzah. Plus, hiding a piece of Matzah alludes to the Torah's instruction "You shall guard the Matzos".
Three matzas represent the Patriarchs, Avraham, Yitzchak and Yaaakov. Avraham was the man of Chesed (kindness and benevolence), Yitzchak of Gevurah (stern discipline) and Yaakov of Tiferet (balance and Torah study). Yitzchak's harshness needs to be broken to allow people leeway in their approach to G-d.