When subjects and verbs agree, it means that the subject of a sentence and the verb must be in the same number. This agreement ensures grammatical correctness in a sentence. Specifically:
- If the subject is singular, the verb must also be singular. For example: "The cat runs fast."
- If the subject is plural, the verb must also be plural. For example: "The cats run fast."
This principle is essential for clear and effective communication in writing and speaking.