substring24

This is not a complete statement or function call. The closing parentheses is missing, and it is unclear what programming language or context this is in.

However, assuming this is part of a function call in a language like JavaScript or Java, the substring function extracts a portion of a string based on the starting and ending indices specified. In this case, the parameters passed in are 2 and 4, which means the substring returned would start at the 3rd character (index 2) and end at the 4th character (index 3).

For example, if the original string was "hello world", substring(2, 4) would return "ll".