What does compute_adjacency_list return?

I am trying to figure out what the mesh method “compute_adjacency_list” returns
Documentation is cryptic and only says that you get an adjacency list…
I get a, array of groups of 5 indices. I am guessing these are 5 indices of vertices that are neighbors?
Looks like this: [{776032, 776041, 850994, 850996}, {776041, 776042, 850995, 850989}, {776033, 851002, 850998, 776039}…]
Does this mean that the mesh is organized in triangles that form pentagons?
is the center of the pentagon a vertex who’s index is the index in the above array?

Any info on this data structure would be great. Thanks!