This is the 13711th most frequent German word.
einverstanden
Agreed.
In this sentence, 'einverstanden' expresses agreement with the subject's proposal, used as an adjective modifying the subject 'Ich'.
Ich bin mit deinem Vorschlag einverstanden.
I agree with your proposal.
Here, 'einverstanden' is a predicate adjective asking about agreement or consent regarding a proposed event.
Seid ihr einverstanden, wenn wir später anfangen?
Are you okay with starting later?
In this case, 'einverstanden' describes a state of mutual consent among the subjects concerning a plan, again used as an adjective.