Simplify the following text for a Grade 17 native English-speaking person.
Original: The coat of arms is a shield with the image of Mount Triglav , Slovenia 's highest peak , in white against a blue background at the center ; beneath it are two wavy blue lines representing the Adriatic Sea and local rivers , and above it are three six-pointed golden stars arranged in an inverted triangle which are taken from the coat of arms of the Counts of Celje , the great Slovenian dynastic house of the late 14th and early 15th centuries .
Simplified: The coat of arms is a shield with the image of Mount Triglav , Slovenia 's highest mountain , in white against a blue background ; below it are two blue lines that stand for the Adriatic Sea and local rivers , and above it are three six-pointed stars arranged in an triangle which are taken from the coat of arms of the Counts of Celje , an important Slovenian family . .