There is _ArrayToString() in standard Array.au3 include file but it's only for one dimensional arrays.
In one of my projects I needed it for two dimensional arrays obtained from Internet Explorer (by IE UDF)
so I have created _ArrayToString2D() and derived _ArrayToHtml2D()
Func _ArrayToString2D(Const ByRef $avArray, $sDelimCol = "|", $sDelimRow = @CRLF, $iStart = 0, $iEnd = 0)
Func _ArrayToHtml2D(Const ByRef $avArray, $attrib = 'border="1"', $iStart = 0, $iEnd = 0)
Here it is