A stone is a rarely used unit for measuring weight, equivalent to 14 pounds. Any weight in stones can be converted into pounds by multiplying by 14.
The stone was developed over hundreds of years in Europe. Many countries, including England and Ireland, used stones for measuring weight, but had different interpretations of precisely how much a stone should be. A standard measuring amount for a single stone was defined, in 1824, when the Weights and Measures Act was passed, applying to the entire United Kingdom. This stone is the modern stone, which is equivalent to 14 pounds in the imperial measurement system. It was abandoned, when the metric system was adopted.