If you are talking to me for legal advice, anything you tell me, or my staff, or any other attorney you might talk with for legal advice, is a privileged communication. In other words, I can't be forced to repeat it, unless you approve it, I can't be forced to repeat it either. Not by the police or a court or another attorney.
But it's not just that I can't be forced to repeat it -- I am not allowed to repeat it, unless you say it's okay (in other word unless you waive the attorney client privilege -- click here to go to the Code of Professional Responsibility on this issue.). If I repeat it and violate the attorney client privilege, it can end up costing me my license -- violating the attorney client privilege is so serious it can result in disbarment, and also subject an attorney to a civil lawsuit for damages.
This is not true with others you might talk with. Tell your brother, tell your mother, or tell your friend anything about your case, and they can end up hauled into court to testify against you, forced to repeat what you told them.
This is an absolutely crucial piece of advice. It is important in anything that could end up going to trial. And to tell how important it is you only need to look at criminal cases and how often a person is convicted based on what they told someone other than their attorney. I've never seen any studies on the matter, but I would be willing to bet that in serious cases, where a conviction carries ten years or more in prison, in at least two-thirds of the cases that go to trial crucial prosecution evidence