Assuming both your workbooks are open in the same instance of Excel which you can confirm by going to the View tab > Switch Windows and seeing if both workbook names are listed:
Sub ModifiedOneCell()
Workbooks("simple av & cv template(Level).xls").Sheets("Table ENG SG") _
.Range("C9:C44").Copy _
Destination:=Workbooks("Finalize").Sheets("sheet1").Range("C9:C44")
End Sub
The help for this can be found by opening the Object Browser in VBA (press F2), scrolling down to the Range object, clicking Copy from the list in the right pane then press F1.
The [space][underscore at the end of lines is the line continuation key combination in VBA allowing you to split long lines of code for readability.
If your workbooks are open in separate instances of Excel (i.e. only one is visible in Switch Windows), then copying to the clipboard and selecting Windows as you did in your code is the correct approach.
You would need to add
Range("C9:C44").PasteSpecial xlPasteAll
in place of
ActiveSheet.Paste
to get the result into the desired range
Ranges don't have a Paste method - only PasteSpecial.