Racial Prejudice – Negative thoughts, feelings or beliefs about a person or group based on their ethnicity/skin colour
Prejudice is negative thoughts, feelings or beliefs about a person.
Racial - related to race - divisions of the human species.
Your race is shown on your face and all (racial) humans can be grouped on the basis of these physical characteristics.
So, racial prejudice combines the two meanings to give:
Racial prejudice: Noticing someone's race and having negative thoughts about them.