It certainly varies by jurisdiction, but this is from the Minnesota Masonic Manual:
THE SECRETS OF MASONRY
Every Entered Apprentice should be informed of the following basic principles and information.
What You Can Discuss With a Non-Mason
Masonry is not a secret society. Members of our lodges are not in anyway forbidden from telling others that they are Masons. While every Mason should remember his obligations to secrecy, yet we want to inform non-masons about who we are, what we are, and what we do. Therefore it is important that every Mason understand clearly which things he can talk about and which things he cannot.
What is a Masonic Secret
What are the things we call the secrets of Masonry? The first secret is the ballot of a Mason. No one can know how a Mason votes, unless that Mason tells him, and that is considered unmasonic conduct. The right and privilege of casting a secret ballot is universally respected in this country by Masons and non-masons alike.
Other secrets are:
• the modes of recognition (signs and words);
• the obligations or vows of each degree;
• the manner of conferring the degrees, and;
• the legend of the third degree.
These four items are usually considered to be the "real" Masonic secrets. But we should all realize that any interested party can go to the public library or bookstore and obtain books which reveal all these things. Clearly we cannot consider these to be secrets in the true sense of the word. There is no way we can keep these books from the public. What then is the meaning of our obligation to secrecy?
Our Obligation to Secrecy
The obligations of Masonry, as well as all other teachings and laws of our Craft, are not things that Masons impose upon other people. These obligations, teachings, and laws are things that each Mason agrees to accept for himself and to apply to himself. Thus when we agree to
keep a Masonic secret we only agree that we will not discuss that matter with a non-mason. This agreement is then binding upon the Mason, but it is not and cannot be binding upon a non-mason.
Masons should not be disturbed by this. If a nonmason learns what he considers to be our secrets, we are under no obligation to take action of any kind. But if the same person comes to us and asks us to affirm or deny that certain things are our secrets, then we must neither confirm
nor deny what they have learned. We are best advised to simply change the subject. If that fails, then let the person read this page.