It's a document that lets the court know that all discovery is complete. It's a way for the court to know that the lawsuit is technically ready for trial.
Once your attorney prepares and files a "Note of Issue" the case will sit on the trial calendar for many months.
When your case is finally called, your attorney will need to appear for a pre-trial conference with the trial assignment judge. During that conference the judge will ask the defense attorney what their position is and whether there is a chance this case can be settled prior to trial.
If there is the possibility of settlement, the judge will likely reschedule another conference date to return and update the court on the settlement posture of both parties.