The equation "x = 4" indicates that the variable x is equal to the number 4. This means that whenever x appears in a mathematical expression or equation, it can be replaced with 4. This is a fundamental concept in algebra, where variables represent unknown values. In practical terms, if you have a situation where you need to find the value of x, knowing that "x = 4" allows you to solve problems more easily. For example, if you have an equation like 2x + 3, you can substitute 4 for x to find the result: 2(4) + 3 = 8 + 3 = 11.