Chinese medicine is built upon many different philosophies that are somewhat interconnected.
In the West, the five-Element theory is probably the best known one
which incorporates the 12-channel theory and is based on Yin and Yang.
The Chinese clock connects those 12 channels to 2 hours each during the 24h of one day.
What does that mean in real life? For example:
You feel tired at 5pm every day, but miraculously pick up strength again at 7pm without having had a nap (- Kidney channel).
You wake up every night at about 3am and find it hard to fall asleep again for quite some time (- Liver channel).
If you have symptoms, pains or problems that keep reoccurring at the same time of the day, it is worth checking which channel is dominant during that hour. It might have a weakness that should be addressed.