The court ruled that it was unconstitutional for government officials to lead public school students in prayer. This included all school officials, such as teachers, principals, or even janitors.
A favorite case for the flying monkey right and other religious conservatives to blame for the trouble in this country, while the conviently ignore all the other changes that have happened. After all, only good things can come from shoving your religion down the throats of others, right? (See Ireland, burning times, The Spanish Inquisition)