This is the 200th most frequent Russian word.
считают
"Считают" means "they consider" or "they count."
In this sentence, 'считают' is used in the sense of 'to believe/consider'. The word illustrates an opinion or belief held by people.
Многие считают, что спорт улучшает здоровье.
Many believe that sports improve health.
Again, 'считают' is used in the sense of 'to consider', showing an analytical or informed opinion in this interpretation.
Ученые считают, что этот метод наиболее эффективен.
Scientists consider this method the most effective.
Here, 'считают' is used in the sense of 'to count', directly referring to the action of calculating or summing something tangible.