Why is the hopfield network a model of associative memory?
An Associative Memory is a synonym for Content Addressable Memory or a memory which stores the result of associative learning, wherein an input item is learned to be associated with an output item.

A Hopfield network is a type of associative memory, wherein an input item (including partial, noisy representations of the original trained/encoded item) is an associated to a the ideal representation of the trained/desired/encoded input item.

For further discussion of Hopfield networks, I recommend look at the question "What&#39;s the difference between a Hamming and Hopfield network?"