Simplify the following text for a Grade 9 native English-speaking person.
Original: The Irn-Bru Scottish Football League First Division Championship is the highest division of the Scottish Football League and the second highest in the Scottish football league system .
Simplified: The Irn-Bru Scottish Football League First Division ( or Scottish First Division ) is a professional football competition in Scotland . It is found on the second level of the Scottish football system , below the Scottish Premier League .