The equation "f(a) = 2" indicates that when the function f is evaluated at the input a, the output is 2. This means that for the specific value of a, the function produces a constant result of 2, regardless of what a actually is. In mathematical terms, f is a function that can take various inputs, but in this case, it is defined such that one particular input, a, yields the output of 2. This concept is fundamental in understanding how functions operate and how they can be used to represent relationships between different variables.