The following code will loop through all the characters in the address field and add them one by one to your hidden field (excluding any spaces). As per your example above the loop will exit as soon as the length of the string is 5 characters.
Put the code in the After Update event of your address field.

Dim S As String, X As Long
    
For X = 1 To Len(Address)
    S = Mid(Address, X, 1)
    If S <> " " Then txtHidden = txtHidden & S
    If Len(txtHidden) = 5 Then Exit For
Next

Thank you!

Kevin, does there happen to be a way to include a filter characters function in this code?

Yes. Just insert the line of code between the 2 If statements.
For example, using Richard's function from the Tech Help video:
txtHidden = FilterCharacters(txtHidden, ALPHANUM)

Filter Characters

Thank you so much

You're welcome.

Okay, another question.  I have now gotten all the data to update properly when entering a new company to create a unique code for each company.  I have so far avoided and false negatives or positives by taking the first and last 3 from the name, the address and all of the zip. Thus far this has worked well.  I got all the different sets put together in a query, but I can't figure out how to make the query figure out the code and update each new company record with it.  

Thank you again.

You could just use a recordset on a button.

Or you could use the query and break down the pieces.

Make new expression to remove spaces
RemoveSpaces: Replace(Address," ","")

New expression for first 5
First5: Left(RemoveSpaces,5)

Then Concatenate that and all your other fields (first3, zip, etc) into one field.

Once you get it figured out in the select query, you can use an Update Queries to change the values in the tables to your new code

I have all that figures out.  I have two hidden fields in the CompanyNameT that take care of reducing the CompanyName to the first part of the code, and two hidden fields in the CompanyT that do the same with the address in the CompanyT.  Then I used a query to pull the hidden fields' information together into one concatenated code.  Now I have to figure out how to attach the proper code to the proper company.  either by adding it to the CompanyT or a making another table for the codes and relating them.  I think that last would work best, but I don't know how to use an update query...or if I need an append.  I used an append to add all the existing codes to a seperate table that I can now relate to the Company T, but I don't know how to make all newly added customers show up on the CompanyCodeT.

I tried an append query earlier, and it kept reproducing all of the ones I had already appended over and over.

I would just make a field in your CompanyT called uniquecode or whatever, then just append all of those codes over or use an update query to re-make them in it. Then you can just put an afterupdate event on your FirstName/ZIP/Address along the lines of this

If IsNull(ZIP) or IsNull(Address) or IsNull(FirstName) Then
'Fields aren't filled out we can't concatenate it
Exit Sub
Else
'Fields are all there, concatenate it and put in the record
uniquecode=    'code that does the concatenating
end if

So all the old ones would have their code, and any new customers that come in will automatically get their code created. Likewise if you change a name/address/zip it will automatically update it as well.

Thank you all so much!