The Glory of the Raider 10 or 25 boost entails completing all 16 achievements necessary for the Glory of Raider meta-achievement while running through the three Lich King raids (Naxxramas, The Eye of Eternity, and The Obsidian Sanctum) in the raid size of your choice.
The first raid meta-achievement introduced in World of Warcraft: Wrath of the Lich King is The Glory of the Raider. The one glory achievement is completed by default. However, you may also buy both Glories of the Raider achievements at once.
You might be curious about the kinds of achievements needed to complete Glory of the Raider meta-achievement before purchasing it. Take the raider Glory of Naxxramas as an illustration. Among the 16 tasks that must be completed by players are things like beating all bosses in 25-man mode with fewer than 21 players, eliminating some bosses very quickly, and even disobeying some boss mechanics to make the fight more difficult.
In addition to being challenging on its own, most groups would not even bother to pursue these accomplishments. The Glory of the Raider boost is the ideal approach to complete this meta-achievement without spending endless amounts of time searching for a capable and committed raid party.