I want to know: how to get from Guangzhou Baiyun International Airport to Guangzhou Jiarui Hotel by bus?

You can take the subway line 3 north extension at the airport (remember it's a subway, not an airport express), then change to subway line 3 (Tianhe Bus Terminal-Panyu Square) at the west subway station (take 7 stops), get off at the exit C of Dashi subway station, then go straight south for about 400 meters and you will see a Minaminoooji turn right, not far away.

If you don't know how to get out of Dashi subway station, you can ask the waiter, because it's about 600 meters away from the hotel, not very far.