It refers to the linguistic analysis, in the area of formal logic, of the sentence “Every farmer who owns a donkey beats it”.
Who would have thought this simple sentence is studied so extensively.
My feeling* is if we analyse semantic of a sentence based on solely its syntactical structure, we will not go very far. It is because a human brain does not parse and understand a sentence in insolation. A lot of lateral association and re-interpretation happens in the process.