I have reviewed this section multiple times, in an effort to understand the concept. However, I need better and more detailed information about this concept, in order to understand the concept and the assessment questions.
Basically, the integration designer consists of the following:
Data model. Essentially a model for any kind of data, for example a Customer (First Name, Last Name, Date of Birth). The model itself is not directly linked to sourcing data - your customers may come from a SQL table, a webservice, or more. The data model essentially describes the "what".
Data views. This essentially describes where Pega gets data from, and how to write data back to a specific system. For example, your customers may be sourced from a SQL table (i.e. a list of customers), but adding a new customer might be done via a POST request. Data views essentially describes the "how" data is sourced.
System of record. This essentially describes the "where" data resides in.
In addition, the integration designer can visualize the integration landscape. This helps you understand the relationships between data types and systems of record.
Please check out some of the following resources - if you have a specific question, feel free to ask anytime.