This is the 2003rd most frequent Russian word.
укреплению
"Strengthening" or "fortification."
In this sentence, 'укреплению' is the dative case of the noun 'укрепление', serving as the object benefiting from the action of 'способствует' (promotes).
Укреплению здоровья способствует регулярная физическая активность.
The strengthening of health is promoted by regular physical activity.
Here, 'укреплению' is in the dative case again, indicating the beneficiary of the factors being studied.
Учёные исследуют факторы, способствующие укреплению иммунной системы.
Scientists are studying factors that contribute to the strengthening of the immune system.
While the sentence doesn't involve 'укреплению' explicitly, it relates to its nominative form 'укрепление', showcasing its thematic usage in conveying the concept of strengthening. This helps students understand its case system and derivations.