A tort has been defined as a "civil crime," an action which is against the law, but isn't a crime. Torts include: automobile accidents, medical malpractice, libel, and most other tupes of personal injury cases.
Torts are usually the result of someone's negligence - a person causing an auto accident because they weren't paying attention, for example. If a tort was committed on purpose, like battery, it's considered an intentional tort.
A person who committs a tort (called a tortfeasor) can be held accountable for his or her actions in court.
Tort reform, then, is the effort to limit when a tortfeasor can be held liable for his or her actions, and to limit how much money a jury can order a tortfeasor to pay to the victim.