the one on the left is called a darning foot or sometimes a quilting or free motion foot. It is used in doing the final quilting stitches on quilts when your feed dogs are down and you move the fabric sandwich around under the needle.
The middle on is a gauge that fits into the walking foot if you want to stitch parallel lines in, the gauge adjusts so the bottom of the arm tracks along a previous stitching line and the needle will stitch a parallel line. The straight,even bar on this foot is the one that fits into the walking foot.
It's hard to tell what the right foot is, but it appears to be a blind hem foot that allows you to set the depth of the stitching for a blind hem (I'm really not sure about this one.)