This video discusses key concepts in algebra including expressions, equations, functions, variables, and operations. It explains that an algebraic expression contains numbers, operators, and at least one variable. Variables act as nouns that represent unknown or changing quantities, while operations like addition or multiplication are verbs that describe actions. The document provides examples of how to write expressions and equations using variables to represent real-world situations involving money earned at a job, numbers of cars on a road, or distance from an object.