Although it's often translated as "rectitude", I find that morality makes it easier to understand. Bushido: The Spirit of Japan defines morality in two ways: as the power of unwavering decision upon a certain course of conduct and more metaphorically as the bone that gives firmness and stature.
‘Morality is one’s power to decide upon a course of conduct in accordance with reason, without wavering; to die when to die is right, to strike when to strike is right.’ Morality is the bone that gives firmness and stature. Without bones the head cannot rest on top of the spine, nor hands move nor feet stand. So without morality neither talent nor learning can make the human frame into a samurai.’
2. Courage 勇
Courage is an extension of morality and only useful when matched with correct morals. Courage, or the spirit of daring and bearing, as it was first translated was a huge element of raising children during this time. Parents challenged their children constantly in Spartan-like training. A far cry from the overprotecting helicopter parents of today.
It is true courage to live when it is right to live, and to die only when it is right to die
3. Benevolence 仁
Samurai, who possessed both the legal and physical power to destroy and kill were also required to keep their powers in check with benevolence and mercy. It is only those who could act with valor to the extent that they can befriend their enemies in times of piece who could capture benevolence.
Indeed valor and honor alike required that we should own as enemies in war only such as prove worthy of being friends in peace. When valor attains this height, it becomes akin to benevolence.
4. Respect 礼
If you've ever been to Japan, you've likely experienced the Japanese politeness or respect. This system is based in Chinese Confucianism but the Japanese Samurai adopted and preserved this system very well. Are you working hard to treat everyone as respectfully as they should be?
By constant exercise in correct manners, one brings all the parts and faculties of his body into perfect order and into such harmony with itself and its environment as to express the mastery of spirit over the flesh.
5. Honesty 誠
As a principle, the Samurai did not lie and there are many tales of those who did being put to death for it. The Samurai also didn't see the need for written contracts as that would be doubting the truthfulness of their word.
Bushi no ichi-gon...was a sufficient guarantee of the truthfulness of an assertion. His word carried such weight with it that promises were generally made and fulfilled without a written pledge, which would have been deemed quite beneath his dignity.
6. Honour 名誉
There is hardly a more profound concept in Bushido than honour. The Samurai lived and died by their honor, with haragiri (seppuku) being the final way of preserving lost honor. Fortunately, killing yourself by cutting your gut open is not allowed in most modernized countries (and definitely not Japan). Still, though, there is a great deal that can be learned from Samurai-esque honor. He was born and bred to value the duties and privileges of his profession. Fear of disgrace hung like a sword over the head of every samurai … To take offense at slight provocation was ridiculed as ‘short-tempered.’ As the popular adage put it: ‘True patience means bearing the unbearable.’
7. Loyalty 忠義
During Samurai times loyalty was thought of as being more valuable than life itself. Loyalty today is fairly nonexistent, but the remainders of Samurai-era loyalty can still be seen in Japanese companies where employees often stay for their entire lives.
Life itself was thought cheap if honor and fame could be attained therewith: hence, whenever a cause presented itself which was considered dearer than life, with utmost serenity and celerity was life laid down. Of the causes in comparison with which no life was too dear to sacrifice, was the duty of Loyalty.