Error in SQL Server

Question

hello!

 

 how to resolve this error and what does that means ?

The 'System.Data.SqlClient' provider is not registered on the local machine

Line 186:        using (OleDbConnection excel_con = new OleDbConnection(conString)) 
Line 187:        { 
Line 188:            excel_con.Open(); 
Line 189:            String sheet1 = excel_con.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null).Rows[0]["ENGLISH"].ToString(); 
Line 190:            DataTable dtExcelData = new DataTable();

.