Translation:You don't understand me!
I am also studying the language so take that into consideration.
From my understanding, 了解 is understanding something/someone through knowing the thing/person for a certain amount of time. It usually comes from familiarity with something. Think of the expression "know something like the back of my hand." The expression is usually used for something you are very familiar with and understand very well. That's why 了解 is often used with a person. For example, when you fail to understand your girlfriend's feelings, you would use 了解.
明白 on the other hand is more like a realization or a revelation. It is that "AHA!" understanding when you figure out something. So, when someone says something to you and goes "y'know what I mean?" Then you would use 明白 to reply. This is why 明白 is often used with understanding the solution to a problem, understanding the gist of what someone is trying to say, etc..
So, I hope you 明白了my explanation, and the more you study Chinese, the more you will 了解 the language.
First of all, please be aware that (as of now 4/22/2020) this course has some mistakes in the audio. Specifically, most, if not all, instances of a single-character audio (such as a one-character tile) for "了" in the female voice pronounces it as "liăo," whereas most (perhaps all) of these cases should be ”le". I hope that hasn't confused you throughout this course!
When Chinese characters have multiple pronunciations, those pronunciations are for different meanings of the character. It's like "wind" in English. "There is a strong wind blowing." But also, "I need to wind my pocket watch." The only way to tell which pronunciation and meaning is intended is from the context. For 了, it is almost always "le," a grammatical particle with several uses. The only instance I know of 了 being "liăo" is as part of this compound word 了解. (Someone mentioned in another forum that there are a few other compound words like 了解.) So, you just have to look at the grammar of the sentence. Could the particle 了 "le" be placed here? Or is this part of a compound word? Specifically, look for 了解.