The expression "2y - 5" is a simple algebraic expression where "y" represents a variable. The term "2y" indicates that the variable is multiplied by 2, while "-5" signifies that 5 is subtracted from the product. This expression can be used in various mathematical contexts, such as solving equations or modeling real-world situations. In algebra, expressions like "2y - 5" can be evaluated by substituting a specific value for the variable y. For example, if y is equal to 3, then "2y - 5" would equal 1, since 2 times 3 is 6, and subtracting 5 gives 1. Understanding such expressions is fundamental in algebra and helps in solving more complex problems.