Can - the word of what part of the speech?

Such words as "can" in the Russian language expressa condition indicating compulsion, opportunity, necessity. They call these words predicatives - words with modal meanings of necessity, necessity, possibility.

Understand the "modal" value should not scare you, because it means it is an individual attitude of the speaker to the information he describes.

At school, these words are not studied as a special part of speech, so the question: can - what part of the speech? It is worth replying that this is a predicate or a word of the category of state.