。
Count the apples in the basket.
Literal
Basket [possessive-の] inside [possessive-の] apple [possessive-の] number [object-を] count-[command-なさい].
A classroom task directive. 籠 (かご) can mean 'basket' or 'cage' depending on context — here it's clearly a basket since it contains apples. 数える ('to count') + ~なさい (soft imperative). The structure '籠の中のリンゴの数' stacks three possessives: 'the number of apples of inside of basket'.