This is the display length of the snippet for any given result in the search results that Google provides. This is on both mobile and desktop. It sort of impacts the meta description, which is how many snippets are written. They're taken from the meta description tag of the web page. Google essentially said just last week, "Hey, we have officially increased the length, the recommended length, and the display length of what we will show in the text snippet of standard organic results."
The new meta data description has gone from From 160 to 230 - 320 characters.