This is the launcher that will transport BepiColombo to orbit. The upper part with the spacecraft and the fairing will be integrated in the final assembly building.
The image captures the transfer of the Ariane 5 launcher from the launcher integration building (at left) to the final assembly building (outside this view) at Europe's Spaceport in Kourou.
BepiColombo is a joint endeavour between ESA and JAXA, the Japan Aerospace Exploration Agency. It is the first European mission to Mercury, the smallest and least explored planet in the inner Solar System, and the first to send two spacecraft to make complementary measurements of the planet's dynamic environment at the same time.