Ciao marple58, advice has two meanings:
1 - guidance or recommendations offered to someone about the best course of action to take in a particular situation: she gave good advice about treating everyone with respect; her help surprised him, but he took her advice.
2 - (in business and legal use) a formal record of a financial agreement or other transaction: cheques and remittance advices were raised in alphabetical order.
Advice is mainly used with the first meaning, and in this meaning it is a mass noun (that is, it has no plural). The business/legal meaning, however, is a count noun: it has a plural form, advices.