This verse comes from the berachah immediately following the Shema. And at first glance, it seems to simply repeat a well recognized assertion: he who follows G-d’s commandments will be blessed.
This reading relies on two translations that could be more nuanced. “Hears” in this reading implies “obeys;” and “commandments” implies simply “laws.” So you will be happy if you do G-d’s will (and don’t get whacked). As they say in the movies, “Move along folks. Nothing to see here.”
But there is a deeper meaning to this phrase, relying on different (but perfectly legitimate) nuances of these words. As Rabbi Art Green points out, “hear” can mean “take to heart,” and “your commandments” can mean “your attempts to bring us together.”
Taken together, the phrase would read, “It is a truth that the person who takes to heart Your attempts to bring us together will be happy.” The language of “commandment” only serves to underscore the urgency behind this prayer. It is as if saying, “You really need to listen, now. You need to hear G-d speaking with you, yearning to be together with you.”
One rather paradoxical facet of these different translations is that they represent very distinct, and diametrically opposed, worldviews. In the first, the language of obey/commandment serves to separate man and G-d. G-d is the commander, man is the commanded, and as anyone with military experience will tell you, officers don’t fraternize with the enlisted.