This is the 170th most frequent Japanese word.
言う
To say; to tell.
The verb '言う' is used in its standard form to indicate saying something, often followed by a direct quote with quotation marks.
彼は「こんにちは」と言った。
He said 'hello'.
Here, '言う' means to state or tell something, often used with abstract nouns to indicate communicating a particular fact or truth.
彼は本当のことを言っています。
He is telling the truth.
In this context, '言う' is used in a passive-like construction ('と言います') to specify what something is called or named.