It's Only Water
When you buy a homeopathic remedy, you are buying a solution of water and nothing else. Nothing but expensive water.
The active ingredient that is supposed to cure the affliction you are suffering from is diluted in water to various levels, the most common of which is 30C. This is a ratio of one molecule of the substance to every 1x1060 molecules of water, the amount recommended by inventor Samuel Hahnemann.
To show the scale of that, here are some examples. 12C is a "pinch of salt in both the North and South Atlantic Oceans." And 12C only has a ratio of 1x1024.
So, statistically there will be no trace of the substance in a remedy. You have more chance of repeatedly winning the lottery every week for the next six months than you do of getting a remedy with even a single molecule of the substance in.
How then is the remedy supposed to work? The water is supposed to remember what the substance it was in contact with. You read that correctly - water is supposed to remember a substance is was barely exposed to. But presumably forget all the other substances it has been in contact with. A deeper explanation of how it is supposed to work can be found here.