Internationalism in linguistics refers to words that are used and understood in more than one language. For example, the word "computer" is an international word because it is used and understood in many languages around the world.
Think of it like a secret code that people from different countries can use to communicate with each other without needing to learn a new language. When people from different parts of the world use international words, they can understand each other without having to speak the same language.
International words can be borrowed from one language to another, or they can be created specifically to be used in multiple languages. Some examples of international words include "hotel", "bus", "radio", "sport", and "music".
Knowing international words can be helpful when traveling or communicating with people from different countries. It can also be useful for language learners who are trying to understand multiple languages at once.