です is a polite copula, an serves the same function as the english words "is", "am", "are", etc.. It's plain form is だ.
A couple of example sentences:
いから です か。 - How much is this?
いから means "how much" and refers to cost rather than quantity. です means "is". か is the polite-form interrogative which makes this sentece a question. Note: the subject of the sentence, "this" is assumed, and therefore not included.
わたしは ベン です。 - I am Ben.
In this sentence, わたし means "I" and です means "am."
In English, we have different copula depending on the subject being linked into the sentence. When the subject is "I", the copula is "am", when the subject is "you", the copula is "are", and when the subject is neighther you or I, the copula is "is." In Japanese, です and it's plain form だ are used as universal copula.
Best of luck in your studies!