What mean of posting class

Hi Sir

We would like to create a invetory code for new product line , the account code will be 14721 .

We understand that the account code posting for inventory is controlled by posting class.

Need to create a new posting class for this new product line.  When we create a new stock item and assign this new posting class, then system will post to these new account code.

My question is what is posting class referring to?

Is anyone can guide me how to do the above create the new posting class in system?

Hope to hear from you soon.

Thank you