I'm completely new to D&D and have run into some trouble with combat. I've read the rules for the Starter Set multiple times and they say when rolling the d20 for attacks, the Ability Modifier and Proficiency Bonus should be added, but say nothing about the Attack Bonus listed next to the weapon name. I'm wondering what to do with that bonus. Is it added to the attack roll along with the Ability Modifier and the Proficiency Bonus? Thanks.
Your Attack Bonus with a weapon consists of your Ability Modifier + your Proficiency Bonus (if you are proficient with that weapon). So the Attack Bonus you are looking at on the sheet is the result of the calculation, included to save you working it out every time, not part of it.