what is exactly a motion for summary judgement and its implications

A motion for summary judgment asked the Court to award judgment on one or more issues, or possibly the whole case, summarily, without a trial.  It argues that, based on facts which are not disputed, the movant must prevail as a matter of law, and therefore there is nothing to be tried. In your case, since the promissory note requires you to pay, you admit you haven't paid and that you signed the promsisory note, and are not claiming that it is invalid for any reason (e.g. fraud, duress, failure of consideration, lack of mental capacity, etc.), the plaintiff is claiming that, based on these undisputed facts, there is no issue to be tried, and it should prevail as a matter of law.  I don't know all the facts, but it doesn't seem as if you have any defense, and I'm not sure what a lawyer could do for you in terms of defending the claim, other than costing you a  lot of money.  However, an attorney may be able to help you negotiate a better settlement than you could on your own.