need a explanation on this paragraph so i can understand better (chap 12)

121 Agreement An essential element for contract formation is agreementthe parties must agree on the terms of the contract and manifest to each other their mutual assent [agreement] to the same bargain. Ordinarily, agreement is evidenced by two events: an o'er and an acceptance. One party offers a certain bargain to another party, who then accepts that bargain. An agreement does not necessarily have to be in writing. Both parties, however, must manifest their assent, or voluntary consent, to the same bargain. Once an agreement is reached, if the other elements of a contract (consideration, capacity, and legalityidiscussed in subsequent chapters] are present, a valid contract is formed. Generally, the contract creates enforceable rights and duties between the parties. Because words often fail to convey the precise meaning intended, the law of contracts generally adheres to the objective theory of contracts. Under this theory, a party's words and conduct are held to mean whatever a reasonable person in the offeree's position would think they meant