A more thorough explanation:

False testimony is when a witness gives evidence that is not true. This can happen in court, in an affidavit, or in a deposition. It is also known as false evidence.

For example, if a witness says they saw someone commit a crime, but they were not actually there, that would be false testimony. Another example is if a witness lies about what they saw or heard in order to help someone else.

False testimony is different from perjury, which is when someone lies under oath. Perjury is a crime, but false testimony is not necessarily a crime.