The phrase "to play up" means to exaggerate or emphasize something, often in a way that is meant to draw attention or create drama. It can be used both positively and negatively depending on the context. For example, if someone is performing well in sports, their coach may encourage them to "play up" by being more aggressive and taking risks. On the other hand, if a news outlet sensationalizes a story, they might be accused of "playing it up."