Eta alone can mean ‘the’, ‘she who’, ‘either/or’, ‘indeed’, ‘than’, or ‘I was’, with the accent helping to narrow it down. Eta+nu is ‘her who’, ‘he/she/it was’, etc.
Also, for example, tau+iota is either an interrogative or an indefinite pronoun, and it is the accent which tells you which without having to scan further through the sentence.