How can you bake a cake if the cake doesn’t exist before baking?

Consider a sentence: He bakes a cake. Assume you don’t know the meaning of the word bake. How would you guess the meaning of the sentence? You would guess a broader meaning of the word bake. Therefore, you would understand the sentence as “He does something with a cake.” The sentence implies that the cake exists before baking. The cake doesn’t exist before baking. Baking is happening for the cake's ingredients, not for the cake itself; the cake is the outcome of the baking. Even though your inference about the meaning of the word bake misleads you about the meaning of the sentence, you won’t be wrong about the meaning of the word bake. Consider another sentence: She bakes a potato. In this context, your guess (She does something with a potato.) is correct since the potato exists before baking.