I will arrive to Zhengzhou Train Station and I want to take bus to the Shaolin temple.

Yes, the Central Bus Station is near to the train station. You can directly walk to there. There are direct long-distance buses that can take you to the temple. The schedules are 07:00, 08:00, 09:00, 10:00 and 11:00. The duration is about 2 hours with the ticket fare of CNY 28 per person.

thank you so much! I plan to take bus from Shaolin to Luoyang, do you happen to know the timetable of that buses? Thanks in advance!

Buses are all passby buses which depart from Dengfeng. Almost 20 buses leave from Dengfeng from 07:00 to 18:30 and it takes around half an hour to Shaolin. So just wait near the main entrance to catch a bus.