This is the 382nd most frequent Russian word.
сил
The word "сил" is the genitive plural form of "сила," meaning "strength" or "power."
Сил here is used to refer to physical or mental strength or energy.
У меня не хватает сил, чтобы продолжать.
I don’t have enough strength to keep going.
Сил is used here to denote the effort or energy required to accomplish something.
Для достижения успеха нужно приложить много сил.
To achieve success, one needs to exert a lot of effort.
Сил in this context refers to the rejuvenation of energy or strength after a pause or rest.