A "No Contest" plea (also known in Latin as "Nolo Contendere" and sometimes called an "Alford" plea) has the same legal effect in criminal court as a guilty plea. The result is that the defendant is giving up their right to a trial and allowing the court to convict.
The difference (as mentioned in the link above) is that in a no contest plea, the defendant is not required to formally allocute, or publicly admit guilt. This means that the defendant's admission is not available in a subsequent civil lawsuit for damages brought by the victim. The plea is also sometimes used when the defendant is not in danger of a civil lawsuit but wishes for personal reasons to refrain from publicly admitting their guilt while accepting a conviction and sentence.
This plea is sometimes called an "Alford" plea because it was affirmed in the case North Carolina v. Alford, 400 U.S. 25 (1970).