'World famous' gives an idea of authority and makes it appear to be something I can trust.
The publishers are said to be 'educational'. This makes it sound as if they are publishing for your own good and not purely for profit.
Learning how to improve your English is made to sound very quick and easy, words such as; 'simple', 'swift' are used. The word 'mastery' makes it sound like you can easily become an expert. 'Double your powers' sounds precise, like a statistic. 'Power' is an attractive speciality.
Starts with a question to get you thinking.
The paragraphs are very short, making it easy to read.
The writer uses patterns of 3 in the second paragraph. This is a traditional persuasive way.
The important information is withheld: We do not find out who the expert is, nor do we discover what sort thing we would have to do to achieve mastery. The promises come first, playing on our insecurities and aspirations, and making us want to read on.
It's set out like a newspaper article.
The layout and tone are that of a newspaper report. It is as if a journalist has discovered this 'fascinating' book, this form creates a sense of detachment, as if no one is actually selling you anything. You expect to believe what you read in newspaper articles.
As you can use there is quite a lot you can analyse in a fairly short text. You may have noticed other devices used, such as the use of Upper Case type for 'world famous'.