An accord is an agreement between groups or even nations, like a formal peace accord that prevents war or the accord between you and your sister specifying who gets to use the car on which days.
Accord is an agreeable word. If you and your best friend are always in accord, you agree about everything. And if you do something of your own accord, you do it without prompting from someone else. As a verb, accord means to be in harmony or agreement, or to allow. Perhaps your enhanced vocabulary will accord you, or allow you, a better understanding of language.