What does corroborate the testimony?

To introduce additional evidence that supports the testimony evidence.

To back it up or give more evidence that proves the testimony is true.

Agree with. Backup. Confirm.

To corroborate is to confirm. If you are corroborating the testimony of another employee, it means that you are formally stating that what this other employee said is correct, to the best of your...

It means someone is using you as a witness; now your employer or more likely a lawyer or Law Enforcement Officer wants you to speak "on the record" about what you know regarding the other employe....