To unlock the Centurion trophy in Cities: Skylines, you will need to name/rename 100 roads. The easiest way to do this is to use the same road that you named Steve for the A Road Called Steve trophy:
Like with that trophy, simply select the inspector tool (the house with a magnifying glass on it at the left of the in-game menu) and press X to select it. Zoom in close enough so that you can see the names of roads, press X to select the road, and then press right on the D-Pad once to select the Rename tool. Type in the name Steve and the trophy will unlock.
Now, go back to the pencil tool and once the text box appears, confirm it. Repeat 100 times which shouldn't take too long and the trophy will unlock.