In the context of relational databases, the term meaningful information refers to information that describes an attribute of an entity represented in a table, such as a customer's first name, last name, address, or phone number.
It might be tempting to use one or more of those attributes in a primary key, but bear in mind that values for those attributes can change.
Customers can change their names, move, or install new phone numbers.
A customer could be entered into the table twice if one customer-relations staff member entered the address as "17^th Ave. SE " and another entered the same address as "SE 17^th Ave.".
When you assign arbitrary values, such as a CustID, to each customer, you avoid these problems.
Regardless of whether customers change their name or residence, you will always have their orders and other information tied to their original CustID value.