ISO 639-2 Is a 3-letters abbreviation standard for language names, like 'heb', 'eng' and 'spa' for Hebrew, English and Spanish.
ISO 639-2 Is a part of the ISO-639 standard a for language names.
The 639-2 part refers to 3-letters abbreviation standard, as opposed to 639-1 which refers to 2-letters abbreviations.
Examples:
heb
: Hebrewspa
: Spanisheng
: English