Minecraft wiki entry for Glowing_Obsidian, associated text: Glowing obsidian makes an appearance in Minecraft: Story Mode - Season Two, spawning around the observer when Jesse places the structure block and on the bottom of the obsidian cages Vos was in.
Glowing obsidian has no name assigned to it, so its in-game name appears as tile.glowingobsidian.name.[1]
Despite this, it can be assigned a custom name using a resource pack with a language file.