Looking for words or phrases to fit the idea of this form of hierarchy

Solution 1:

taxonomy or nomenclature could both be used to describe that, although taxonomy is generally used in nature.

Solution 2:

This type of structure is usually referred to as a tree. Following this analogy, the individual words are nodes, where "spelling" is an end node or leaf, "languages" may be the root node or just root, and "languages/english/spelling" is a branch.

The wikipedia link says "The lines connecting elements are called branches", but I do not fully agree with that. It is common language to refer to all nodes below one node as a branch.

Solution 3:

This is almost, but not quite, an example of hyponymy, used ‘when the meaning of one form is included in the meaning of another’ (George Yule, ‘The Study of Language’). In your example, languages is a ‘superordinate’ and English is a hyponym of languages. The structure breaks down with spelling, because that’s an aspect of English rather than a kind of English. Hyponyms of English might be Standard English and Caribbean English.

Solution 4:

I'd like to propose breadcrumb trail, which according to the Wiktionary is:

A trail of hyperlinks that lead consecutively to the current page, displayed in the page as a guide and a means of navigating easily to any of the pages in the trail

The Wikipedia continues:

Breadcrumbs or breadcrumb trail is a navigation aid used in user interfaces. It allows users to keep track of their locations within programs or documents.

Typical breadcrumbs look like this:
Home page > Section page > Subsection page