A 2A football classification means the high school has fairly low enrollment compared to the rest of the high schools in the state. High school football classifications vary from state to state but depend on student enrollment, with small schools in class 1A and larger schools in higher classes.
Each state's athletic or activities association decides the number of classifications and where to set enrollment cut-offs to disperse teams as evenly as possible amongst the different classifications. Many states use between four and seven classifications.
Generally, winners of games against other teams in the same class can make it to state playoff games, so the more classes there are in a state, the more teams have a chance of making it to the playoffs. The purpose of high school football classifications is to give more teams chances to play in playoff and championship games.
The underlying assumption of the football classification system is that teams from schools with smaller enrollments cannot compete with teams from schools with larger enrollments. Smaller schools may have less funding for their sports teams and less competitive tryouts. Larger schools may have more funding and more candidates vying for spots on the team, making tryouts more competitive.