1. The practice of magic. This is the most common meaning and refers to the use of supernatural powers or spells to achieve effects. Think of the classic image of a wizard with a long beard, pointy hat, and a wand, casting spells and summoning creatures.
2. Exceptional skill or ability. This meaning is less common, but it uses the magical connotations to suggest someone who is incredibly skilled in a particular field. For example, you might say "He performed the surgery with incredible wizardry," meaning he did it with great talent and finesse.
The term "wizardry" often carries a sense of wonder, mystery, and power, whether it's referring to actual magic or just extraordinary skill.