Similar to integrity.

Keeping their word; doing the right thing even when nobody is there; considering the impact of their actions etc.

It's projection. Someone sees a trait they like in someone else and think they themselves possess, so they cast it into a positive light as "good character".

One becomes a "person of character" by building a reputation of integrity through interactions with friends, neighbors, co-workers, clients and strangers, which can be backed up by references and reviews in the business world, and/or in a casual sense by the way one is introduced to others.

People can tell how one feels about another by their subtle manner inferring respect and importance or non-importance. A person of character also carries him/herself with confidence and grace, because of true self esteem, no pretense.

If one is a good person and is true to that all the time, it will become apparent to others, and therefore "boom" a person of character.

Always do what you think is right, not what you think people want you to do.

You become a person of character by getting a guest spot on the Simpsons and getting drawn by Matt Groening.

Habitually acts in virtuous ways. Aristotle had a nice list. See the photo.

By doing the right thing whether anyone is watching or not.

Tell the truth. Keep your promises. Be kind to those around you. Pay your bills on time. Practice The Golden Rule.
Drive carefully, etc etc etc,