Overwatch – Understanding Numbers When Destroying Non-Player Objects

From your comments that you may have switched heroes during your games, it appears to be a percentage of each game played * 1 per each win. So if you won four games where you played D.Va for 75% of each of the games and Mei for 25%, you would have the D.Va bar show 4*0.75 = 3 wins and Mei would show 4*0.25 = 1 win.

These bars obviously wouldn't show up as whole numbers most of the time if you switch heroes often during games as it is unlikely that you would end up with exact amounts of whole games played. It seems to round numbers to the nearest whole, so each of those games that you won that you played the character for less than 50% of the time slightly fills up the bar but is labelled as "0 wins."

There is no official lore for what the numbers mean but I would presume they are version, unit or batch numbers. I doubt they reference a specific kind of Omnic robot as Bastion is the type, not his name as might be thought.

From Overwatch's website character lore

Originally created for peacekeeping purposes, Bastion robot units possessed the unique ability to rapidly reconfigure themselves into an assault-cannon mode.

(Emphasis added)