The adjective Jewish, refers to something related to Judaism. It can refer to someone who is a Jew by birth, practice or self-identification. It can also be used to describe a thing associated with Judaism, such as a Jewish holiday. The English word is always capitalized because it is based on a proper noun (Jew).
Jewish is not a language. Someone who incorrectly uses the phrase "speaking Jewish" may be referring to speaking Yiddish, Hebrew or Ladino or one of a few other languages that are associated with Jews in other parts of the world, usually a blend of a local language and Hebrew.
The term "Jewish star" usually refers to the Star of David.
Despite a large body of work in films, TV, theatre and concerts, I am viewed by many as a Jewish artist. I do not resent the label, except for the fact that I disapprove of labels in general.