On Transact SQL language the nvarchar is part of unicode character strings data types and have variable length. The string length must be a value from 1 through 4,000.

Nvarchar syntax:

nvarchar [ ( n ) ]
nvarchar [ ( max ) ]

Nvarchar example:

USE model;
GO
CREATE TABLE nvarcharTable ( a nvarchar(25) );
GO
INSERT INTO nvarcharTable VALUES ('This is an example');
GO
SELECT a FROM nvarcharTable;
GO