This is the 454th most frequent Japanese word.
言える
"Can say" or "able to say."
言える here functions as a potential form of 'say', used to express a possibility or a subjective claim.
彼の努力の成果は成功と言える。
His efforts' results can be said to be a success.
言える expresses a potential statement about the quality of the book.
この本は全ての人におすすめできると言える。
This book can be said to be recommendable to everyone.
言える is used to propose a hypotheses about the voice.