This is the 2400th most frequent Turkish word.
güçleri
"Strengths" or "forces" (plural form).
Here, "güçleri" means "their powers" and indicates the strengths or abilities of a group as a noun in the possessive form.
Onların güçleri herkesi etkiledi.
Their powers impressed everyone.
In this context, "güçleri" represents natural forces as a possessive form.
Doğa güçleri ormanları şekillendirdi.
The forces of nature shaped the forests.
Here, "güçleri" refers to "forces" in military or organizational terms, again in a possessive form.