Any legal work involving more than one country is “international” – whether it’s because the parties to a contract dispute or an internet communication are from different countries, because products are shipped from one country to another, or because an investment in one country is made by a government, business entity, or individual of another country.
Some kinds of work, like immigration, export controls, and foreign exchange, are uniquely international, while others, like sales transactions, lawsuits and arbitrations, or mergers and acquisitions, are the “international” equivalent of domestic legal work.