What is the value of the expression 5 squared?

The value of the expression 5 squared is calculated by multiplying the number 5 by itself. This can be mathematically represented as ( 5^2 = 5 \times 5 ). When you perform this multiplication, you find that ( 5 \times 5 = 25 ). Therefore, the correct answer is 25, which means that option C is indeed the value of the expression.

Understanding the concept of squaring a number is fundamental in mathematics, as it lays the groundwork for more complex operations and properties of numbers, particularly in areas like algebra and geometry.