Dog
The word Bob in this sentence is a noun.
She gave a terrific speech yesterday.
He gave a wonderful speech at his inauguration.
Free speech is a human right.The best man gave a speech at the wedding.
Ronald Reagan gave the speech following the challenger disaster in the oval office.
The above is a simple declarative sentence.
"You gave the book to her" is a complete sentence made up of several parts of speech. You - pronoun gave - verb the - article book - noun to - preposition her - pronoun
Phylis quite zanily gave the dog a bone.
The word 'in' would be a preposition in the example sentence you gave.
The man appeared deranged as he gave a speech to the traffic at the intersection.
He gave the speech in a confident manner.
Weak is an adjective in that sentence. It describes the noun "answer".