Your Hebrew name is your Jewish ID. You will need it every time you are called to the Torah, when you sign your ketubah, and when you are sick. Those who mourn you will need it for your funeral.
A Hebrew name consists of a name, a relationship, and the names of those through whose merit a person claims membership in the Jewish people.
For example: My name is רות, Ruth, and בת, (daughter) followed by the names of those through whose merit I am a member of the Jewish people: in my case, אברהם ושרה, (of Abraham and Sarah) since I became Jewish as an adult. A male who was born Jewish might be named דוד (David) בן (son) יעקוב ורבקה (of Jacob and Rebecca, his Jewish parents.)
What if you don’t know your Hebrew name? First, if your parents are living and are Jewish, ask them (ask for their names, too, while you are at it.) If it has been forgotten, look for any documents that might have it: a bris certificate, a naming certificate, or a bar/bat mitzvah certificate.
If you never received a Hebrew name, it isn’t too late! Talk to your rabbi. Tell them you didn’t get a Hebrew name and you want one. It is, after all, your Jewish ID! The rabbi can help you choose a name (perhaps a Hebrew form of your legal name, perhaps another name meaningful to you.) It is never too late for a naming.
What is your Hebrew name? Do you know why it was chosen for you? Or if you chose it, why that particular name?