We can illustrate that from the human realm also. Some people are mechanically inclined and enjoy building things. I have a friend who likes to restore antique cars. He tears them apart and puts them back together again. He knows them inside and out, right down to the last nut and bolt.
People are normally familiar with the things they build.
Since He obviously knows all there is to know about everything He made, we are driven to the inescapable conclusion that He has complete and accurate information about everything there is. I certainly cannot make that claim. I am not very mechanically inclined, and when I put something together there is no guarantee that I will remember how it works the next time I use it. Some time ago I purchased a bicycle rack for my automobile so my wife and I could get away and enjoy a little togetherness. I followed the instructions carefully, installed the rack on my car, and we had a great time together.