This is a noble title that can only be awarded to those that have made outstanding contributions, so have been awarded this "life title" by the current monarch. It can not be inherited by their spouse or children.
The contribution can be for exemplary service in the military, intellectual, philanthropist, or invention contributions, even writing a song to commemorate the death of a beloved noble.
The making of an outstanding contribution to society, their specialized field, the award for bravery, being wounded in war saving others, or the Crown.
They are "dubbed" by the Sovereign or their deputy during a special ceremony, called an investiture. Usually, there are 30-60 individuals that are being awarded different honors. They are awarded by the Queen or someone of the Royal Family.
They have no official duties, although they can be called upon to make speeches about their field of study or anything pertaining to the award. They are often given liaison jobs to show the public that the Monarchy has a representative there.
They are able to use the title of Sir or Dame, Lord or Lady.
They are allowed to wear a sash, ribbon, or jewelry with their awarded badge in their clothing or as an accessory.
In previous years, this title was gifted to special "friends and family", or as awards for completing vital missions.
They are often used as liaisons, ambassadors, and negotiators, or assistants of such.