The following “honors” are social advancements granted to your character. They represent social mobility, earning ownership of something (like a castle or lands), etc.; they are not “learned talents” but “earned privileges”.
Any honor that has an asterisk (*) grants a “title”. A title is something you are recognized by. While not prohibited by the rules, it is strange for someone to have multiple titles. Someone with multiple titles has often lived a very storied life.
If you’re killing trolls in a dungeon, you aren’t suddenly going to exclaim, “Oh! I am noble now!”- an honor should be appropriate to the story. Taking an honor can kind of force it to manifest in game, maybe your GM adds “…and for their brilliant leadership, I am bestowing Grax a noble title!” to their list of rewards for slaying trolls. That being said, they don’t dictate the story. Always check with your GM before taking an honor to see if it is appropriate.
You can be knighted in game for service or a gallant deed. You do not need to take the “Knight” honor to formalize this. However, taking the “Knight” honor after being knighted allows you to capitalize on your station and benefit in ways others would not. It shows you putting effort into your station, and you reap greater rewards as a result. Think of it like this: anyone can be given a sword but few learn to wield it.
It is possible that your in-game actions may cause you to lose an honor. A castle can be sacked, political infighting might deprive you of a title, etc. If such a thing happens, you have two choices: retrain it (as you can do with a feat or feat equivalent) or work with your GM to gain another similar benefit (if it is appropriate to the story). Your honor isn’t automatically or instantly restored but you should get a replacement relatively soon after losing it.
Because we believe that the world should react to players and the players should be involved in communities they impact. Honors introduce a social aspect to the game that shows the players aren’t just “getting better at stabbing things” with each level but are growing socially and as people in their own right.