A principled person is someone who can say a thing and stand by it without compromise.
There are people who will say a thing and you will have to check it, again and again, to ascertain it's durability and it's level of sincerity.
And there are also some other people who will speak and you do not have to be scared if it is correct or not, to me that describes such a person as being a principled person.
When you are principled, it reflects in every of your word and actions as well, it makes you stay on top of your game and you become admired by a lot of people.
The respect that comes along with it cannot be overemphasized.
When you see a principled person, make sure that you never take them for granted, value them with all that you have and place them in a very high priority.