If you're the defendant in a criminal case, one of the most important questions your attorney may ask is not, "What did you do?" but "What can the prosecutor prove that you did?" In fact, a good part of your attorney's job may focus around suppressing evidence in your case.
So, what exactly does that mean? In plain terms, it means making sure that the jury never hears or sees that particular evidence in your case. That way, it cannot be used against you. This isn't something underhanded or "sneaky" on the part of a defense attorney -- it's actually a critical part of aggressively defending your rights under the law.
When you've been charged with a crime, particularly a complex white collar crime like embezzlement or fraud, the prosecution has to prove several distinct elements of its case beyond a reasonable doubt. If the prosecutor fails to prove any one of those elements, the case falls apart.
Part of your defense attorney's job is to look at the evidence against you and see if any of it has been obtained through illegal or unconstitutional methods. In some cases, it may not be clear whether the evidence was obtained legally or not. Your attorney will then seek a judge's ruling on any "questionable" evidence to see if he or she agrees that it should be suppressed. Naturally, the prosecution will put on an equally aggressive argument about why the evidence should be allowed in your case.
Motions to suppress evidence -- and the legal wrangling afterward -- can take a great deal of time in any case, but they're often very productive for the defense. So, if your attorney is talking about suppressing evidence in your case, pay close attention to what's happening and be prepared for the possible wait. The eventual outcome may be worth it.