Short form, one of the most advanced projectile weapons technologies is one step closer to reality.
A convention gun or cannon uses a propellant, in most cases gunpowder, to accelerate a bullet up to speed. This is an instantaneous reaction. The powder ignites and kicks the bullet down the barrel of the gun, the expanding gasses pushing it along.
A rail gun launches the projectile down the barrel between a pair of electro-magnetically charged rails (hence the name). This accelerates the projectile the entire duration of its trip down the barrel making for a far faster projectile. This speed allows for greater firing distance, greater accuracy, and greater hitting power.
There are even more upsides to a rail gun. You don't have to store bags or shells of potentially volatile gunpowder. The projectile itself will fly at such high velocity that it does not even need to have a warhead. We call these Kinetic Kill Weapons.
The downside, Railguns are power hungry. If you ship can't supply the needed energy then the gun simply won't fire.
Still, this technology has long been a staple of science fiction and had a resurgence in many shows, books and movies, replacing or supplementing the ubiquitous laser or plasma weapons. It will still be decades before a man portable railgun or coilgun is reality, but once these are fielded on board surface combatants, and their potential is realized I would fully expect to see heavy research into putting them into land vehicles, first as heavy artillery pieces, then on tanks, followed by aircraft and once power supplies are efficient enough into man portable units.
Now for those wondering why there is still a big fire plume when this launches, that is simply heat friction. That projectile leaves the barrel at Mach 7, so the air in the barrel is flash ignited simply by the heat generated by a body moving that fast. The projectile itself in this case is also non-ferrous, but uses a conducting sabot body to accelerate it, that is the bit that falls away right after launch.