On the same page means agreeing and understanding things the same way. Get everybody on the same page, are we on the same page, not on the same page.
It is office language and describes shared understanding rather than agreement about what to do. The picture is of a group reading from one book together.
1phraseon the same pageAgreeing and understanding things the same way.
“Before we start, let us make sure we are all on the same page.”
on the same page is a phrase.
Practised in Idioms