However, if you wish to combine different strings of text in formula mode, you would need to use the + sign between the two variables you're using, as shown below.
You can also combine variables with static text strings as below.
As well as combine static text strings.
If you're trying to combine variables that are not strings, you can simply convert the variable into a text string format by adding .to_s behind the variable pill. The following will give you "[item name] - [sales account code]"