Today's agenda is the re-election of the student council. If anyone wants to run, please raise your hand.
Literal
Today [attributive-の] agenda [topic-は] student-council [attributive-の] re-election [about-についてです]. Someone run-for-office-want person [subject-が] exist [if-たら] hand [object-を] raise-please-[てください].
Student council meeting. ~について ('about, concerning') is a standard topic-marking pattern. 改選 ('re-election') is specifically for re-electing existing positions. 立候補する ('to stand as a candidate, to run for office'). Classic student council announcement style.