This is the 756th most frequent Japanese word.
高齢
"High age" or "elderly."
Here, '高齢' is part of the compound '高齢化社会' (aging society), referring to societies where a significant portion of the population is of advanced age.
高齢化社会が進む中で、多くの人々が新しい問題に直面しています。
As aging societies progress, many people face new challenges.
'高齢' is used directly to describe someone's advanced age, emphasizing her active lifestyle despite her age.
彼女は高齢にもかかわらず、毎日ジョギングを欠かしません。
Despite being elderly, she never misses her daily jogging.
In this sentence, '高齢' is used as an adjective to describe the employees as being of older age.