This represents the sum of heat, producing from the tool. There are products with different watts. They are suitable for doing several works. As it is an indicator of power, it is better to buy a compatible with the device.
Buying a powerful iron does not necessarily mean- it is the better one. Rather, focus on the purpose. In the marketplace, a variable wattage soldering iron is available. The standard unit commonly available is 20-60 watts.
When you lower the power within 5-25 watts, it becomes suitable for thin wires. Also, circuit board and other components with light duty. The iron can weld wires, jacks, and various guitar parts with a 25-40 watts range. However, for repairing audio cables and broad sections you need 40 or more watts.