[Roritharr]

>In mathematics, the lakes of Wada (和田の湖 Wada no mizuumi) are three disjoint connected open sets of the plane or open unit square with the counterintuitive property that they all have the same boundary. In other words, for any point selected on the boundary of one of the lakes, the other two lakes' boundaries also contain that point.

"disjoint connected open sets" - What is an open set? What does disjoint connected mean?

"plane or open unit square" - I know what a plane is, but the context of an "open unit square" which doesn't make sense to me shakes my confidence in that.

"on the boundary of one of the lakes" - What did we just define as a lake?