A more thorough explanation:

In law, equity refers to a set of remedies and procedures that are different from legal ones. Legal remedies usually involve money, while equitable relief involves injunctions, specific performance, or vacatur. Courts award equitable remedies when a legal remedy is not enough. For example, if a claim involves a unique piece of real estate, the court may award equitable relief.

The distinction between legal and equitable remedies originated in England, where there were separate courts for each. In America, some states created chancery courts that only deal with equitable relief. Today, most courts can prescribe both legal and equitable remedies.

Courts are sometimes hesitant to impose equitable relief because it requires monitoring the defendant's compliance with the court order. However, the Supreme Court has encouraged the use of equitable remedies in certain areas of law.

For example, in CIGNA v. Amara, the Supreme Court held that for violations of ERISA, the aggrieved party may be entitled to "obtain other appropriate equitable relief" in addition to legal remedies. In Montanile v. Bd. of Trs. of Nat'l Elevator Indus. Health Benefit Plan, the Supreme Court narrowed the scope of equitable remedies for ERISA violations.

John Norton Pomeroy's A Treatise on Equity Jurisprudence is an authoritative source on equitable remedies in the United States.