What do you need to know in bearing business? Thank you very much for your advice.

This? Alas, things in China are different from those in foreign countries. This kind of manufacturing mainly depends on contacts, and professional knowledge is not very important.

However, if the landlord just wants a simple understanding and no one is training, then go to the bookstore to buy one or two books on the basic knowledge of bearings to avoid making jokes when communicating with customer technicians.