Here's a breakdown:
* Oui: Means "Yes"
* j'accepte: Means "I accept"
You can also say "Je l'accepte" which literally means "I accept it" and is used when you are accepting something specific.
For example:
* Oui, j'accepte. (Yes, I accept.)
* Je l'accepte. (I accept it.)
* Oui, j'accepte votre offre. (Yes, I accept your offer.)
* Oui, j'accepte le poste. (Yes, I accept the position.)
You can use the first phrase for general acceptance and the other phrases for specific situations.