5. The person reading K'riat Sh'ma blesses [God] beforehand and afterwards. During the day, he makes two blessings beforehand and one afterwards. At night, he makes two blessings beforehand and two afterwards.

Q1: Why does Rambam tell us the number of B'rakhot (blessings) recited at each time of K'riat Sh'ma? - in the next Halakha, he will briefly describe each one; we could figure out how many there are from there.

A: The number has its own significance - either because of "seven praises for God" to be recited daily, or else to make the "meditations" of day and night equal. (Yerushalmi)

Q2: Why are there two B'rakhot beforehand both times, but the number changes afterwards between daytime and nighttime?

A: Again, either to complete the "seven praises" - or to add an extra unit to the nighttime (B'rakhot + ) K'riat Sh'ma. As to why the additions are made after K'riat Sh'ma and not before, it may be that

Q3: What is the function of these B'rakhot? Are they associated with the Mitzva of K'riat Sh'ma - just as we make a B'rakha before doing other Mitzvot? Are they contextually appropriate around K'riat Sh'ma?

Rambam, Copyright (c) 1999 Project Genesis, Inc.