The phrase "to enter into" means to become involved in or commit oneself to something. It can be used both as a verb and an idiomatic expression. When used as a verb, it means to start participating in an activity or agreement, such as entering into a contract or joining a group. As an idiomatic expression, "to enter into" is often used to describe the process of forming a relationship or partnership with someone or something else. For example, one might say that they are "entering into negotiations" with another party in order to signify their intention to begin discussions towards reaching an agreement.