These are a much overlooked feature of Excel, largely because array functions can be hard to understand. The power of many regular formulas such as countif, sumif that you use every day can be increased significantly by applying them to arrays.
What are they ?
Array formulas returning lists of values
Finally, you can use transpose to have afConcat display horizontal arrays using transpose- try this entered as an array with control/shift/enter
=afConcat( TRANSPOSE (aFRow))