In Greek mythology, Pandora released evils when she lifted the lid of her container.
Hesiod says the container held destructive troubles that had previously been kept away from human life. When Pandora opened it, these evils escaped and spread among humankind. The myth uses the event to explain why suffering, illness, and hardship exist in a world that had once been free from them.
The surviving Greek wording is broader than a modern inventory of named problems. It refers to many kinds of human misery, including pains and diseases, rather than presenting a single villain or monster. That is why “evils” is the most faithful short answer to this question.
The familiar phrase “Pandora’s box” also shifts attention toward the container. In Hesiod’s earliest surviving version, the vessel is a jar, and the emphasis falls on the release of troubles. The English expression later became a general metaphor for an action that creates many unforeseen problems.