Final answer:
The second section of the Liber Abaci is focused on Roman numerals and notation, marking an important step in transitioning European mathematics from Roman numeral usage to the more advanced decimal positional number system.
Step-by-step explanation:
The second section of the Liber Abaci does not primarily describe the Fibonacci numbers and sequences which the book is most famously known for elucidating. Instead, this section of Fibonacci's work is centered on Roman numerals and their notation systems. Fibonacci's text played a critical role in the evolution of mathematical practice in Europe, primarily through the introduction and advocacy for the adoption of the decimal positional number system, which replaced the less efficient Roman numeral system. This marked a significant shift in mathematical methodology and underpinned subsequent advancements in the field, including developments in algebra.
Considering the broader context, the Liber Abaci can be understood as an instrumental text in transitioning European mathematics from its Roman legacies toward the more advanced mathematical systems that would dominate the Renaissance and later periods. Although notable for many mathematical concepts, the second section specifically deals with transitioning from Roman numerals to the decimal system.