The word agree has a few meanings. For one, it’s a synonym of concur. For example, if you believe the same thing I do with regard to something then you agree with me on that. If you don’t then you are wrong.
Agree can also be synonymous with consent. For example, you might say, “She agreed to go out with me.” You might say that; unfortunately, I don’t get to say it often because that’s just the way my life goes. I mostly sit at home babbling at my computer.
Agree can also mean consistent with. For example, one might say, “The way she acted toward him did not agree with how she felt toward him.” I wish.
Agree might also be used to reflect a food’s effect on your health. For example an extra large helping of deep-fried lard topped with five extra-tart pickles and smothered in wasabi paste might not agree with you if you have a weak stomach. D’ya think?
The word agree is also used in discussions of grammar. For example, when you write a sentence their nouns and verbs should have agreed in number, person, gender and tense, unlike in this sentence.