Hi, I'm going to Beijing on a business trip, I will have two free days.

In the first day, you can visit the the Mutianyu Great Wall. When you go back to the city, it has been afternoon, and you cna visit Houhai. Taste some local food and do a simple shopping, then go back to yout hotel.

The second day, you can visit Tain’anmen Square and the Forbidden City in the morning, and visit temple of heaven, Beihai Park in the afternoon. Then go back to the hotel.
It will be a bit tight, but if hire a taxi, it will be better.

Thank you Ben