In homeopathy, a symptom is cured by a medicine that creates that same symptom. For example Poison Ivy creates a raised, itchy rash with vesicles. If someone comes into a homeopath's office and has a raised, itchy rash with vesicles, the homeopath will give them Poison Ivy (note that if someone gets a rash from Poison Ivy, the homeopath will not give the person more Poison Ivy. That method of treatment is called Isopathy). This law of cure is termed "like cures like".
"Like cures like" is hard to wrap your head around. The way I like to think about it is that your body is telling you what it needs. If you get abnormally hot, your body is saying it wants something that makes it hot. If you get muscle aches, your body is telling you it wants something that gives you muscle aches.
Therefore homeopathy is personal and simple; all that is needed for cure is careful observation of yourself.