This is the 2570th most frequent Russian word.
соглашению
"Соглашению" means "to the agreement" (dative case).
The word "соглашению" is used in the dative case, indicating motion towards an agreement in a figurative sense.
Мы пришли к соглашению о цене.
We reached an agreement on the price.
Here, "соглашению" is part of the phrase "по соглашению," demonstrating the instrumental meaning of agreement being the method by which the contract was ended.
По соглашению сторон, контракт был расторгнут.
By mutual agreement of the parties, the contract was terminated.
In this usage, "соглашению" shows belonging, as it is receiving the action of being followed, in the dative case.