[5e] Character sheet question

Hello. I have a question about the 5e character sheets. I have all of the information for a weapon attack filled in on the sheet, but when I use the "roll" feature, the math doesn't seem to add up on the actual roll. I'm thinking that it has more to do with me not understanding what the first two numbers are on the attack. There is one number, then a vertical line, then another number that says it is to hit AC. What are those two numbers? Thank you in advance for any help you can give me.

The two numbers separated by a vertical bar that you are referring to are respectively an attack roll, and an advantage/disadvantage roll. If you mouse over either inline roll , a tooltip will appear that shows exactly what factors into those rolls. Typically, an attack roll will include a d20 being rolled and an ability modifier being added.

Hi there, as taken from the wiki, I think this is what you're looking for: Why are there two rolls when I make an attack, save or ability check? Every attack, save or ability check roll is deliberately made twice to allow for ease of use with the advantage/disadvantage mechanic that comes up frequently in 5e play. The intention is that if you are rolling with neither advantage or disadvantage then the second roll is ignored and only the first roll is used. If however you have advantage, then you choose the highest of the two rolls, and if you have disadvantage then use the lower of the two rolls. Hope this helps :)

Thank you Silvyre and Louis, that was very helpful! After reading the DMG for a bit, I was thinking that may be the case, but the clarification was much appreciated. You guys are awesome.