This is the 12760th most frequent Russian word.
крепких
"Крепких" means "strong" or "firm" in the genitive or plural form in Russian.
The adjective 'крепких' is used here in its plural genitive form to describe abstract successes ('успехов'), emphasizing their significance or strength.
Желая другу крепких успехов в работе, я верю в его способности.
Wishing my friend strong success in work, I believe in his abilities.
The word 'крепких' here describes the plural noun 'деревьев' in the genitive case, indicating that the trees are robust or solid.
Мы встретились в лесу среди крепких и высоких деревьев.
We met in the forest among sturdy and tall trees.
In this instance, 'крепких' modifies the plural noun 'отношений' in the genitive case, implying the relationships are enduring and well-bonded.