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Python allows for operators to be overloaded (the subject of a separate future Q&A). The `/` operator doesn't strictly mean division in a mathematical sense; it means whatever the operands define it to mean - but we *may call* the operation "division" regardless. (Specifically, we say "true division" to refer to the operation implemented by `/` - this is to distinguish it from "floor division", implemented by `//`.)

In this case, the left-hand side is a type that implements a `__truediv__` method (which implements the `/` operator); so Python translates the operator into a call to that method: `HOME_DIRECTORY.__truediv__("file.json")`. Strings don't implement this, but whatever `HOME_DIRECTORY` is, does.

The semantics, of course, depend on the type of `HOME_DIRECTORY`. However, based on the context, we can infer that `HOME_DIRECTORY` is an instance of the standard library `pathlib.Path` type. The `pathlib` library is designed specifically to support this sort of operation, to make it easier to work with file paths. In this case, the code simply joins up the path, creating a new path that represents "the file `file.json`, within the `HOME_DIRECTORY`".

Thus, `HOME_DIRECTORY.__truediv__("file.json")` is roughly equivalent to `os.path.join(HOME_DIRECTORY, "file.json")` - except that it starts and ends with a `pathlib.Path`. The `os` module also defines a `PathLike` *protocol* implemented by `pathlib.Path`, which allows you to use a `pathlib.Path` in most places that you'd use a path string.

Of course, the reason we use "division" for this operation is purely mnemonic: `/` is the default path separator (the one that Linux uses natively, and one which the Windows runtime will translate automatically). So given `x` and `y` path components, `x / y` intuitively makes sense as a way to put them together into a longer path.