The construction we talk about in art is the same core skill involved in constructing houses or chairs or dioramas. It involves being able to break things down and understand how they were made from three-dimensional materials, so you can build similar things up with such materials from scratch. This information is then used by us when we are developing drawing mannequins or reasoning through designs. The more you understand about how the world around you is crafted, the more base knowledge you have to construct from.
Most of the difficulties we have when drawing from imagination come from a lack of exposure to how things actually work. By living cozy lives where we've never had to consider the proportions of something you want to sit on, of course we're confused by how to even rough in a chair proportional to a character. In having never needed to repair or build something sturdy enough to bear weight, of course we're going to get the leg positions incorrect or struggle with adding the details of how things attach.
With easy access to photographic references, artists today get around a lack of hands-on construction skills by leaning heavily on large collections of object photos they replicate into their work. If they're not sure how to draw a chair, they simply find a photo or 3D model of a chair that suits the scene and carefully inspect all its details. This is fine, and it's technically still construction to follow an existing blueprint. But the stronger your understanding of how things are made, the more of your own designs you'll be able to come up with from scratch without sacrificing believability (https://lib.hol.ink/index.php?topic=39).
This skill is used heavily in the constructive approach (https://lib.hol.ink/index.php?topic=38) to art.