What is a non contiguous range in Excel?

There is no such thing as a non-contiguous range. A range is a group of cells that are together in a rectangular block. Non-contiguous refers to cells that are not touching. So you can have more than one range which do not touch, so what you have are non-contiguous ranges. It is possible to select non-contiguous ranges by first selecting one range and then while holding the Ctrl key, select other ranges.
There is no such thing as a non-contiguous range. A range is a group of cells that are together in a rectangular block. Non-contiguous refers to cells that are not touching. So you can have more than one range which do not touch, so what you have are non-contiguous ranges. It is possible to select non-contiguous ranges by first selecting one range and then while holding the Ctrl key, select other ranges.