Confidentiality isn't professional courtesy, it's the condition without which therapy doesn't work — people don't tell the truth in a space they aren't sure of.
Concretely: nobody receives information without your written consent. Not your employer, not your family, not your partner, not your GP. That you attend therapy at all is as confidential as what you discuss there.
The exceptions are narrow and must be explained in the first session. If your therapist didn't mention them, ask — a professional has them ready. Clinical notes are protected too and kept separately from everything else.
Two situations that frequently confuse people. Couples therapy: confidentiality here operates for the couple as a unit, and the policy on what happens to anything said in individual sessions has to be agreed explicitly at the start. Adolescents: they have their own confidentiality from their parents — parents receive the direction of the work and what they can do at home, not the content of sessions. It is the only condition under which a teenager talks.