Ticket details on website says include tribunes (grandstands). One opposite Grand Prix start - new one opposite endurance pits (assume will be open by next week), and one overlooking Eau Rouge and half of the Ardennes.
You might find this helpful as first time spectators (although we will need to update for the new grandstand after we have been there next week) -
https://www.pistonclick.com/spa-francorchamps
Enjoy - its an amazing location.