Right, yes. So that’s a tileset. It’s a collection of images instead of the ascii (letters and numbers and symbols from the keyboard).
If you did not find the tileset line I mentioned in your settings, you’re probably using the console version, which uses ascii.
I would recommend you get the launcher I linked above. You can install the game version that uses the pictures like that screenshot you showed.
If you already use the launcher, make sure you have the ‘tiles’ dot marked.
If you’re opposed to using the launcher, you can download the graphical versions from this page: https://cddawiki.chezzo.com/cdda_wiki/index.php?title=Download#Downloads_2