This is the 662nd most frequent Japanese word.
鳥
Bird.
'鳥' refers to a bird, specifically the subject 'this bird' being described in the sentence.
この鳥は青い羽を持っています。
This bird has blue feathers.
'焼き鳥' refers to a specific dish in which meat is skewered and grilled, incorporating '鳥' contextually to mean bird as in the main ingredient.
焼き鳥は日本の伝統的な料理です。
Yakitori is a traditional Japanese dish.
'鳥' represents a bird seen flying in the sky; it's a generic mention of a bird as a category.