How to add/concatenate string in Excel

The CONCATENATE function in Excel is designed to join different pieces of text together or combine values from several cells into one cell.

The syntax of Excel CONCATENATE is as follows:
CONCATENATE(text1, [text2], …)

Concatenating the values of several cells
The simplest CONCATENATE formula to combine the values of cells A1 and B1 is as follows:
=CONCATENATE(A1, B1)

Concatenating a text string/formulas and cell value
There is no reason for the Excel CONCATENATE function to be limited to only joining cells' values. You can also use it to concatenate various text strings and formulas to make the result more meaningful.
For example:
=CONCATENATE("Last Updated: ",TEXT(TODAY(), "mm/dd/yyyy"))