In the context of video games, a trainer is a software tool that modifies the game's behavior in real-time. Trainers can provide players with advantages such as unlimited health, mana, or gold, among other features. These tools are especially popular among gamers who want to explore the game's content without the constraints of difficulty or resource management.
If you’re wary of external tools, DA:O has built-in options: Dragon Age Origins 1.05 Trainer