As can be seen from the back cover (below), the main idea is to use these printed tiles to figure out where your miniatures are and what distance they are to critical (or otherwise) points of interest.
Essentially, they are printed card stock of dungeon corridors and rooms (e.g., a Wizard's Lair, a Spiral Staircase, A room with Beds, etc.). Indeed, this set is a combination of earlier sets that were sold separately (Dungeon Floor Plans 1, Dungeon Lairs, Caverns & Dungeon Rooms). Is is printed to a (at the time) high quality standard and an array of possible layouts is easily achieved in next to no time.
Many of the corridor sections contain squares that are the same size as the regular Warhammer miniatures, enabling distance to be accurately measured quickly and ranges to be computed easily. Moreover, in games of Fantasy Roleplay, the squares can be used as "steps" to move the miniatures along with (e.g., the Elves get to move 6 spaces per turn, but Humans only go 4 …. or at least that's how we played these kind of things when using them in conjunction with rules such as Dungeons and Dragons).
When the corridor sections are appropriately cut out (with scissors!) they can readily connect up the disparate rooms and bring a dungeon to life. That said, the contents of the pack is more aligned with Fantasy Roleplay than it is with battles. Not that battles cannot be had in the dungeons. Dwarves against Goblinoids can occur very nicely. But the narrow width of the corridors can make for intense games, perhaps akin to 40k's newer Zone Mortalis sets, or the older Space Hulk rooms. Hence I mostly have fond memories of using these card sets for games of Dungeons and Dragons rather than skirmish battles using Warhammer rules. But even today, the set remains viable and usable. I'd certainly be happy to return to using them in Roleplaying games!