The UEFA Pro Licence is a coaching licence from UEFA, the official governing body of European football. The licence is the highest coaching certification available and follows the completion of the UEFA 'B' and 'A' licences.
A UEFA Pro Licence is required by anyone who wishes to manage a football club in the top level of a European nation's league system on a permanent basis, i.e. more than 12 weeks (the amount of time an unqualified caretaker manager is allowed to take control). This applies to both the head coach or team manager, and such a licence is also required to manage in the UEFA Champions League or UEFA Europa League.
References
UEFA Pro Licence Wikipedia(Text) CC BY-SA