New to Amex. What is the hotel credit?

I recently got the Amex platinum card. Trying to figure out if the $300 semi-annual hotel credit includes the room charge or if it is just for incidentals and extras charged to the room.

Just hoping for come clarification before I book so that I know how much to expect.

And I know it is only for the Hotel Collection and Fine Hotel + Resorts listed on the website. Please let me know if I have misunderstood anything.