It's a WW2 Iron Cross 2nd class. I can't say for sure if it's real or not (but iirc there should be a makers stamp on the other side of the envelope, I believe most were made in Hanau). The medal itself looks real enough, it's not terribly uncommon, about 4,5 million of these were awarded for bravery or other contributions on the field of battle. The one thing that gives me pause is the envelope. Without actually having reference litterature on hand I would say the typeface is wrong but I can't be certain. If you want to know for sure, have it appraised by a professional.

Get a magnet, Iron Cross 2nd Class medals were highly standardized since they were produced in large numbers. It should have a magnetic center, however, if it doesn't it doesn necessarily make it fake, non-magnetic versions do exist.