Which word in the sentence needs correction: "They was excited about the event?"

In the sentence "They was excited about the event," the word that needs correction is "was." The subject of the sentence is "they," which is a plural pronoun and requires the plural verb form "were" instead of the singular "was." In English grammar, the subject and verb must agree in number. Singular subjects take singular verbs, and plural subjects take plural verbs. Therefore, the correct form of the verb in this sentence should be "were." The corrected sentence would read: "They were excited about the event." This ensures that the subject and verb are properly aligned in terms of number.