What the MEB platform is
MEB stands for Modular Electric Drive Matrix — in German Modularer E-Antriebs-Baukasten — the Volkswagen Group platform for battery-electric vehicles. It is not a single car: it is a set of shared dimensions and components that different models are built on.
The battery is the floor
On an MEB vehicle the battery pack is built into the floor between the axles rather than packaged around a combustion drivetrain. Two things follow from that. The mass sits low and centred, which is where a heavy pack does the least harm to the way a car behaves. And the space that a transmission tunnel and an engine bay would take is free, so the wheelbase can grow and the overhangs shrink without making the vehicle longer.
One floor, many vehicles
The same floor scales from a compact car to an SUV to a van. Scaling a platform only works if the parts inside it are standardised, and the battery module is the clearest example: instead of a bespoke module per model, the pack is filled with a repeating module of fixed dimensions. A larger vehicle takes more of them, not different ones.
Why that matters if you are not Volkswagen
A standardised module format creates a supply of that module. Cell manufacturers build to the format, tooling exists for it, and the modules turn up in the catalogues of module suppliers — which is how a bus builder, a marine integrator or a storage system builder ends up using an automotive module. The Avantis Energy module range lists MEB modules alongside the VDA formats for exactly that reason.
The next question is usually the number itself: see where the 590 in MEB 590 comes from.