Which part of speech often shows direction or how different things relate to each other?

The part of speech that often shows direction or how different things relate to each other is a preposition.

Here's why:

* Direction: Prepositions help us understand the location of something in relation to something else. For example:

* "The cat sat on the table." (Where is the cat?)

* "We walked through the forest." (What direction did they walk?)

* Relationships: Prepositions can also show how things are connected or related:

* "The book is about history." (What's the subject of the book?)

* "She was angry with him." (How does she feel towards him?)

Some common prepositions include: on, in, at, to, from, by, with, for, about, through, over, under, beside, behind, and many more.