〜になる

〜になる expresses change-of-state — "become X." The construction varies slightly by what precedes:
• Noun: 学生になる — "become a student"
• Na-adjective: 静かになる — "become quiet"
• I-adjective: drop い, add くなる — 寒くなる — "become cold," 大きくなる — "grow bigger"

The construction is intransitive — it describes X coming to be the case, not someone making X be the case. The transitive counterpart is 〜にする / 〜くする — "make [something] X." 部屋を静かにする — "make the room quiet."

なる is the workhorse verb of change in Japanese, and a major typological difference from English. Where English often uses adjectives directly with "get" / "become," Japanese consistently uses なる: "It's getting cold" → 寒くなる. Stative-progressive 寒くなっている = "is in the process of getting cold" or "has gotten cold."

A polite or honorific reading of なる appears in fixed honorific constructions (お〜になる as the honorific verbal pattern), which is a separate grammar point.