I came across this vba code from https://www.snb-vba.eu/VBA_Fill_combobox_listbox_en.html for filling combo boxes and for the life of me I can't understand this line of code for getting the unique values in a column, I have never seen some of these vba functions before and I want to understand how this line is working before I use it in code.
ComboBox1.List = Application.Transpose(Filter([transpose(if(countif(offset($A$1,,,row(A1:A100)),A1:A100)=1,A1:A100,"~"))], "~", False))