A more thorough explanation:

Testify

To testify means to give evidence as a witness under oath. If someone gives false or misleading testimony, it is called perjury. Refusing to testify can be considered contempt of court, unless there is a valid reason for the refusal.

• A witness was called to testify in court about what they saw on the night of the crime.
• The defendant took the stand to testify in their own defense.
• If you are called to testify in court, you must tell the truth or you could be charged with perjury.

These examples illustrate how testifying involves giving evidence or information in a legal setting, usually in a court of law. Witnesses are often called to testify about what they saw or heard in relation to a crime or legal case. It is important to tell the truth when testifying, as lying under oath can have serious consequences.