This is the 2250th most frequent Russian word.
заключить
To conclude, finalize, or enter into (e.g., a contract or agreement).
In this sentence, "заключить" refers to making a formal agreement or contract.
Мы решили заключить соглашение о сотрудничестве.
We decided to conclude an agreement on cooperation.
Here, "заключить" signifies completing or finalizing a business transaction.
После долгого обсуждения они смогли заключить сделку.
After a long discussion, they managed to finalize a deal.
In this context, "заключить" means to confine or imprison someone.