Ikea's primary brand tenant is their ability to ship and store all of their goods very efficiently because they break down to pack into very flat boxes with little wasted space. For example, a big bookshelf is sold in only flat pieces so the package you leave the store with is the size of a box of cereal. This is how Ikea makes money over their competitors and is able to warehouse huge inventory at their retail locations. Customers also love it because it means you can buy a couch and load it into the back of your small car since it isn't assembled.

In this case I assume it means the bike is disassembled in key places to maintain an extremely low profile and densely packed box.