Unconscious bias is the collection of attitudes and stereotypes we associate with people without conscious knowledge
Implicit or unconscious bias is the collection of attitudes and stereotypes we associate with people without conscious knowledge.
You often see this in UX research as only interviewing people with a limited set of profiles for example race, age, gender, ability or socio-economic status, or choosing to interview underrepresented groups but asking potentially offensive questions.
You may feel uncomfortable interviewing people with different life experiences than you. Reflect carefully on your own behaviour and ask others to point out our biases to help you become aware of them.