Hi. Are you asking what 1-2, 1-3, and 2-5 are? If so 1-2 is generally what no-limit hold-em with a small blind of $1 and a big blind of $2 is called, 1-3 is no-limit hold-em with sb of 1 and bb of 3, and 2-5 is no-limit hold-em with sb of 2 and bb of 5. Basically the review is saying the book is good/applicable to low live stakes hold-em.