** WSDL full form ia Web Services Description Language. This is XML based language to describe the web services and how to access them.
** A WSDL file contains a description of everything involved in calling a SOAP web service:
The service URL and namespace
The type of web service (probably function calls using SOAP, although as I mentioned, WSDL is flexible enough to describe a wide variety of web services)
The list of available functions
The arguments for each function
The datatype of each argument
The return values of each function, and the datatype of each return value
** Universal Description, Discovery and Integration (UDDI) is a directory service where businesses can register and search for Web services.
** UDDI uses WSDL to describe interfaces to web services
You can use Mikalai Zaikin MZ's study notes for further reading.