Abstract concepts in mathematics refer to those concepts that do not depend on specific objects or examples, but only rely on logical relations and rules. These concepts are usually not directly observed or perceived, but understood and mastered through reasoning and proof.

Understanding abstract concepts in mathematics requires some thinking training and habit formation. First of all, we need to learn to extract general laws and structures from specific problems, which is the process of abstraction. For example, we can abstract the definition and nature of sequence from the specific sequence problem, and thus get the general sequence theory.

Secondly, we need to learn to express abstract concepts with symbols and formulas. Mathematical language is a highly formal language, which can accurately express complex logical relations and rules. By learning and using mathematical language, we can better understand and master abstract concepts.

Finally, we need to consolidate and deepen our understanding of abstract concepts through a lot of practice and application. Mathematics is a highly practical subject, and only through practical operation can we truly understand and master abstract concepts.

Generally speaking, understanding abstract concepts in mathematics requires us to have the ability of abstract thinking, master mathematical language and deepen our understanding through practice. Although it may take some time and effort, once we master these skills, we can find endless fun and challenges in the world of mathematics.