Understanding is a mental process like any other cognitive ability we have, and requires, first of all, the acknowledgement of the object, processing the details it includes, and then analyzing said details in order to expand our acknowledgement to a state where optimal if not complete understanding will be reached. The more complex the object is, the more mental effort and energy we would require in order to understand it as best as we are capable.
Any understanding, as said, first requires some degree of acknowledgement to the object at hand, and without any acknowledgement whatsoever, understanding cannot technically begin. Even if, for example, you don’t recognize a country you don’t believe it has the right to exist, you still acknowledge it by calling it in a name. Acknowledgement therefore does not have to be only on the realistic level, as we are able of acknowledging objects as existent even if we think they are mere illusion or work of fiction.
After acknowledgement is reached, that the object at hand exists as either reality or illusion, we ought to process the information it contains. Acknowledging the existence of a book, for example, does not make us understand its content instantly. Therefore we ought to read the book, or process any other information about it, in order to better know it as more than just a perceived object.
And likewise with reading, without any analyzing what we have read, we cannot, theoretically, reach a state of understanding, as understanding requires a conclusion to be reached, and in order to reach a conclusion, whether it’s true or not, we ought to analyze the received information. Analyzing does not have to be complex — there could be many times where it is superficial and/or quick. As I, for instance, find that I have traffic on my site, I don’t have to do a lot of thinking in order to reach a conclusion about the nature of the traffic. It’s more of philosophical, and/or academic issues and subjects that require further, more complex verbal analyzing.
Things are understood, therefore, by three levels: Acknowledgement, processing and analyzing. Take note that understanding does not have to be correct, or at least completely correct, in order for it to be achieved. Much of our understanding is up to interpretation, if not widely disagreed, because understanding largely depends on the conclusion we reach, and said conclusion can be subjective. True knowledge, however, is objective and isn’t relative to the said 3 levels that require for the achievement of understanding, even though understanding is possible, obviously, of true knowledge as well, assuming said knowledge is indeed true and not false or deceptive.
In other words, understanding can be correct as it can be incorrect, and our own degree understanding of something, does not guarantee true knowledge, even though true knowledge indeed requires understanding. It is a one-sided connection — “A” necessarily requires “B”, but “B” doesn’t always lead to “A”.