Hi Amylynn1003 and thanks for your question.
Biotin is a member of the B-complex group of water-soluble vitamins. Water-soluble vitamins are stored in the body in very limited amounts and are excreted through the urine. Therefore, it is a good idea to have them in your daily diet.
Biotin can be found in a wide variety of foods including eggs, liver, yeast breads, whole grains, sardines, legumes, mushrooms, and cereals. Cauliflower, peanuts, and cheese can also be nutrient-dense sources of this vitamin. Fruits are generally not good sources.
There is some highly preliminary evidence suggesting supplemental biotin can help to reduce blood sugar levels in people with diabetes. Biotin may also reduce the symptoms of diabetic neuropathy, though other supplements have much stronger evidence. Even weaker evidence suggests that biotin supplements can promote healthy nails and eliminate cradle cap (a scaly head rash often found in infants).
Basically, taking biotin supplements or ensuring there's biotin in your diet is safe. Whether it will help strengthen your hair and nails isn't really clear.
Does that help?