The expression "48x13" represents a multiplication problem where the number 48 is multiplied by the number 13. This operation is a basic arithmetic calculation that can be solved to find the total product. In this case, multiplying these two numbers results in 624. Multiplication is one of the four fundamental operations in mathematics, alongside addition, subtraction, and division. It is often used in various real-life applications, such as calculating total costs, determining areas, and solving problems in fields like engineering and finance.