ETS2SAPJ : This likely stands for (or similar regional map mods like "South America Project Junior").
sc23638 : Likely a server ID or internal tracking number from a file-sharing site (like ShareMods or ModsBase). sc23638-ETS2SAPJ.part3 (2).rar
A .part3 file cannot be opened or "read" on its own. To extract the content, you must have all other parts (part1, part2, etc.) in the same folder. You usually only need to right-click "part1" and select "Extract Here" using a tool like WinRAR or 7-Zip . ETS2SAPJ : This likely stands for (or similar
Euro Truck Simulator 2 is a popular truck driving simulator by SCS Software. It has a massive modding community. The File Name: To extract the content, you must have all
Do you have the of this download, or are you having trouble getting the mod to show up in your game ?