I did not understand your code, can you put it to me in simple terms? also can you tell me why this code fails? (7 test cases failed)

n = int(input())
arr = map(int, input().split())
first_max, second_max = 0,0
for current in arr :
    if current > first_max :
        first_max, second_max = current, first_max
    elif current > second_max :
        current = second_max   
print(second_max)