Frege-Church ontology is a way that grown-ups talk about how we understand language and what the words mean. It's like playing with blocks and trying to figure out how they fit together to make a big tower.
Imagine you have a box of blocks with different shapes and colors. Each block represents a different idea or concept that we use when we talk about things in the world. For example, the blue block might represent the idea of "water," and the red block might represent the idea of "fire."
Now imagine you want to use these blocks to build a tower that represents a sentence, like "The water is cold." You would take the blue block for "water" and put it on top of the pink block for "is" and then put the green block for "cold" on top.
What Frege and Church were interested in was figuring out how we can make sure that the tower we built represents the meaning of the sentence we want to say. They wanted to figure out how to make language work like a well-built tower that doesn't fall down.
Frege came up with the idea that the meaning of a sentence is made up of the meanings of the individual words and their relationships to each other. So, the blue block for "water" has a certain meaning, and when you combine it with the pink block for "is," it creates a new meaning that is related to both words. Then, when you add the green block for "cold," you get the full meaning of the sentence.
Church added to this by saying that we can understand meaning not just in terms of individual words, but also in terms of the structure of the sentence. So, the blue block for "water" might mean something slightly different in the sentence "The cold water was refreshing" than it does in "The water was cold."
So, Frege-Church ontology is a way of understanding how we use language to represent the world around us. By figuring out how the individual pieces of language fit together, we can create a tower of meaning that accurately represents what we are trying to say.