Is this a legit product page?

Yes, this is an official Xbox One S console listing.

Can you buy a hard copy (disk) of the game and play it on this unit? Internet is too slow here to download a game.

This is a standard Xbox One S console and includes a Blu-ray disc drive to support games on physical media.

What does it mean by past generation

This is not the newest xbox available. A newer generation console available is the xbox series. However this xbox s is still compatible with the current games released.

Can I play newest version of Flight Simulator on this console?

Regarding Flight Simulator, the Xbox release date has not been announced yet. We will share more information regarding the Xbox release in the future.