The rank of a rational elliptic curve can be seen as a measure of how complex its arithmetic structure is. Roughly speaking, you can imagine that a curve of rank r has a substructure of dimension r. So a curve with a high rank is a pretty exotic object. This curve here has a 30-dimensional (or greater) lattice substructure. You can think of it as being possible to arrange the rational points on this curve into a predictable structure in a vector space of dimension at least 30. In that space, there would be at least thirty independent directions in space that could be combined together to produce distinct rational points on the curve.

To really quantify how exotic, it's conjectured that curves with rank 2 or greater have an asymptotic density of zero. That doesn't mean they don't or can't exist, but it does mean they become vanishingly rare, so finding even individual examples of high-rank curves has been absurdly hard.