In Servoy, a developed application is called a "solution". A solution in general contains a set of forms (the equivalent of layouts, UIs or screens in other platforms) and business logic.
Solutions can also contain just business logic, to be used for server side processing using Servoy Batch Processors or to expose through the Servoy Headless Client, for example as a webservice.
Solutions are developed using Servoy Developer which is available as a plugin for Eclipse or can be downloaded pre-packaged with Eclipse from the Servoy website.
For more information on developing solutions in Servoy or on Servoy Developer, see the following guides:
Servoy Development Reference Guide
Servoy Programming Guide
Servoy Developer User Guide