I will take a look at the video here at a meeting and get back to you.
So the source table that has actual code value of Loan Type. There is a cross reference/dimension table somewhere in the model where you can join on load_type_id and get the name value.
In your mapping you will need to do a lookup to that table on the load_type_cd to get the name field. That field you can move downstream to get the name into the target.
I created the lookup. I also selected the return, which is the description. What would be considered the target. Adding to the joiner is not correct. I know because I got an error "A path from the source [Read_Deal] must lead to a target. [ID: PATH_DOES_NOT_LEAD_TO_TARGET] Read_Deal" when I did that.
You should be able to drag the description field from the lookup into the same group as the source read_deal.