As a Noun:
1. Something provided to the public by a government department, organisation or system such as transport, information or help (material, monetary, or personal). English = service.
2. The process of being looked after in a shop or a restaurant by finding you products or by taking your order and bringing you food and drinks. English = service.
3. The cooperation and exchange of information between different organisations or between different sections of an organisation; or the person whose job is to provide such a service. English = liaison; liaison officer.
As a Verb or Adjective:
1. To provide a service, to serve.
2. Of organisations or people, to work together and to keep each other fully informed. English = liaise.