Language-agnostic means that something is not tied to a specific language. Think of it like a toy that can be played with by kids who speak different languages.
For example, imagine a game where you have to add up numbers. The game can be played by a kid who speaks English, Spanish or any other language. That game is language-agnostic because it doesn't depend on a specific language.
Similarly, programming can also be language-agnostic. This means that a programming concept or principle can be used in different programming languages. For instance, the concept of loops is used in many programming languages such as Python, Java, and C++. This concept is language-agnostic because it applies to multiple programming languages, and you can use it regardless of the language you are programming in.
In summary, language-agnostic is a fancy way of saying that something can be used or applied without depending on a specific language.