The information is in the quick install guide (page 3) that should have come with the unit. If not, you can go to
http://support.dlink.com/dgs-1024d and select which hardware revision you have and view/download the QIG there.
IEEE - Enables/Disable IEEE 802.az EnergyEfficient Ethernet Feature (on by default)
Flow Control - On or Off (on by default) - from wiki - Flow control is the process of managing the rate of data transmission between two nodes to prevent a fast sender from overwhelming a slow receiver.
Port Isolation and Storm Control - (off by default) When enabled, a broadcast storm control threshold value of 128 kbps will be applied to incoming broadcast packets on all ports. Also ports 1 to 23 will be isolated from each other, but will still be able to communicate with port 24. Port 24 will be able to communicate with all the ports available on this switch.
If you do change a DIP switch, you will need to power cycle the switch for it to take effect.