Mean is the average number in a set of data. To calculate mean, you add up all the numbers in a set of data and divide that sum by the amount of numbers you just added up. Example: numbers: 2, 2, 1, 3. 2+2+1+3=8.
You wear your wedding ring on the left hand, the finger next to your pinky finger. It is usually the third finger of the left hand, but there's no rule saying that it has to be that finger. In some parts of the world people wear it on their right hands, and in other parts of the world wedding rings are not worn at all.
After the wedding day, wear your engagement and wedding rings however you like them best. Again, the most popular way in the US is to have them both on the ring finger of the left hand with your wedding band first, but you can separate them and wear them on opposite hands, or you can wear your wedding band solo.