As a side note, weren't Trayvon's phone records from that night erased from his phone?
It means to answer questions or make statements under oath. It is okay to lie to the media, the press, the public, investors, customers, contributors, voters — but even lawyers fear being put under oath to answer questions because it brings with it the legal penalty of perjury.
As far as the phone records for that night, the defense didn’t get them for that night and that night only. That could mean that they were erased, or never recorded, or that the state wants the defense to think that they were erased or never recorded. The latter most likely.