A plea of Nolo Contendere comes from the Latin meaning "I will not contest." Some lawyers call it a "no contest" plea. Essentially, an individual is admitting that the Commonwealth of Pennsylvania has enough information/evidence to obtain a conviction and agrees to accept the punishment that is handed down from the Bucks County judge. It is not an admission of guilt.
In my experience, a "nolo plea" is not used frequently because they still must be accepted by the judge. Judge's like to see that an individual is accepting responsibility for their actions and crimes. In a Nolo plea, they are not doing so. Thus, if the facts are egregious or there is no substantive reason for an individual to plead nolo, a judge may not accept such a plea.
Frequently, these pleas are entered to avoid exposure on a companion civil case. If a person pleads guilty in a criminal case and they are being sued in civil court for the issues arising out of the criminal case (i.e. personal injury), the guilty plea can be used as an admission. But, a plea of nolo contendere cannot be used as an admission in a civil suit.