This summary is not the rule. The rule text controls.
This rule says that people can only refuse to testify or share information if there's an actual legal reason allowing them to do so. You can't just decide on your own that you don't want to answer a question or hand over a document in court. The right to stay silent or keep something private has to come from the constitution, the rules of evidence, or another rule the state supreme court has approved.
In practical terms, this means courts won't recognize made-up excuses for refusing to testify or share evidence. If you want to claim a privilege, like attorney-client privilege or the right against self-incrimination, it has to be a privilege that's officially recognized by law. Without that legal backing, you're expected to answer questions, produce documents, or let others testify when asked.
This rule also stops people from blocking someone else from testifying or sharing information, unless a real privilege applies. For example, you can't tell a friend not to answer a lawyer's questions just because you don't want them to talk. The block only works if the law specifically allows it in that situation.