He (subject) is (copula) like (preposition) a (determiner) bamboo (adjective) pole (noun) . The underlined portion is called a subject complement, and it's a prepositional phrase in form: it's headed by the preposition "like", which takes the noun phrase "a bamboo pole" as its object. As for function, you need to determine if the prepositional phrase, "like a bamboo pole" renames the subject (noun; nominal predicate), describes the subject (adjectival predicate) or tells us where or when (adverb of time or place).
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