Yes, the word 'hills' is a noun (a common, plural, concrete noun) and the object of your sentence.
likes
His favorite colour is green because he likes green hills and he likes green trees
bob the builder invented it cause he likes building
Marc likes to paint to show harmony, they are peaceful
The predicate there is "likes ham"and the subject is Pop.
What I did was I invited them over and waited for the right peaceful time then I told them not to freak out then I told them
It means that she does what she wills to do.
he never comes here. He likes other places better.
You can translate the sentence "She likes to go with her friends" by "elle aime sortir avec ses ami(e)s".
The noun in the sentence is girlfriend, object of the preposition 'with'.
Sunny is used as an adjective in this sentence.
Sentence diagramming the sentence, My friend likes this puzzle, will take a few lines drawn within the sentence. A vertical line should be drawn between friend and likes because likes is the verb. Another vertical line should be drawn between this and puzzle because puzzle is the noun. There should be a slanted line just below friend with the word my on it.