This is the 5568th most frequent Japanese word.
きゅうり
Cucumber.
Here, 'きゅうり' is used as a noun referring to the food item, cucumber, and its role in a dish.
きゅうりはサラダに入れて美味しいです。
Cucumber is delicious when added to salad.
In this sentence, 'きゅうり' is again used as a noun representing the item being interacted with — emphasizing safe handling while preparing it.
きゅうりを切るときには注意してください。
Please be careful when cutting the cucumber.
Here, 'きゅうり' is used as the object of the verb '苦手です' to express a personal sentiment regarding cucumbers.