How to add text strings in MS Excel?

Actually, it is very easy. You just need to use the 'text related function CONCATENATE. This same is also used in SQL Server (all versions).

Here are three screen shots which are self-explanatory.

Bringing up the functon CONCAT in Excel.

Inserting the variables 'Jay' and ',Krishnaswamy' into the function.

 The result of evaluating the function

More here,

CONCAT function - Office Support (microsoft.com)