Final answer:
The semicolon in "-2; a" serves as a separator in a list or sequence. If 'a' is -2, then the sequence contains two instances of -2, but without further context, this does not represent an operation or transformation of the number.
Step-by-step explanation:
The semicolon in "-2; a" typically does not have a mathematical meaning on its own but can serve as a separator in the context of a list or sequence of numbers.
If given a context where the semicolon is understood to mean something specific (such as in some programming languages), the interpretation might differ.
However, based on standard mathematical notation and assuming that there is no additional context that attributes a particular meaning to the semicolon, we can only infer that it is separating two values, -2 and 'a', which are in a list or a set.
If 'a' equals -2, then the list or set simply contains two instances of the number -2. Without further context or instruction, the sequence "-2; a" with a = -2 does not change or represent any operation or transformation of the value -2; it would still represent the same numeral, -2, listed twice.