A fictional character is a person in a work of art such as a video game, novel, play, opera or movie. If it is a made-up person or imaginary person (not someone who really or actually lived) it is a "fictional character". Some examples are Kermit the Frog, Yoda, SpongeBob SquarePants, Bambi, Tod and Copper, or Bart and Lisa Simpson from The Simpsons.
The word character can also mean "personality". We can say that someone has a "strong character" meaning a strong, confident personality. It is sometimes used as a noun in this sense: "He is a real character" (meaning someone you cannot easily forget).
A character role in a play means one of the people in the play who have a particular character (personality). They contrast with the main characters of the play. For example, there may be two lovers who are the main characters of the story. The character roles might be: a wicked step-mother, a kind nurse, an old wise man, a stupid fool, a domestic worker who is very old etc.