I am not sure what you are asking. If you created a PDF on your local hard rive, are you asking if anyone else can see it? PDf is just a file and anyone who has an access to \the hard rive on your computer can see it. If I do not have access to your computer I cannot see it. If you upload this PDF to some Web site anyone who has access to this Web site can download your PDF and can see it. If you email this PDF to me I can see it.
Does this answer your question?
Or do you mean that you distributed your PDF to many people and wonder if anyone who gets hold of it can see it? If this is what you're asking then the answer is that you can encrypt your PDF in Acrobat and only those people who are authorized to open this PDf can see it. Acrobat provides two encryption methods: password encryption and certificate encryption. Password encryption is simpler but there might be vulnerabilities in the dissemination of the password. Definitely do not communicate it in the same email as PDF. Certificate encryption is more selective but requires more work. You need to have a Digital ID with a private key to encrypt and certificates with public key of all possible recipients of your PDF at the time you encrypt PDF. Each PDF recipient needs to have Digital ID with the private key installed on his computer. You get the certificate with public key that you include on the encryption.
You can Google "certificate encryption in Acrobat" you will get links to tutorials that show how to use this feature.