That's an MFM controller. All three headers are for hard disks. The larger one is daisy-chained, the smaller ones are for one drive each.

There's normally nothing to set by jumpers. I'm pretty sure the jumper is for connecting an activity LED.

derSammler is right. It likely is an MFM/RLL controller for ST506/ST412 type fixed disk drives.
It is als likely that Jx is for the activity LED. Back then, "Jx" was used not only for jumpers,
but all kind of 2-wire connections with that same pin connector.

Further googling revealed that..

"wd14c17" is a WD Multi Controller chip
"wd1015" is a Buffer Manager Control Processor
"wd10c23" ia Self-Adjusting Data Separator
"wd2010b" is a Winchester Disk Controller/Formatter

Some of them are mentioned in the Winchester Controller OEM Manual for the WD1002. 😀

If the controller contains an EPROM or microcontroller with built-in storage,
running debug.exe and executing "G=C800:5" (return) will bring up the low-level
routine for MFM/RLL drives. But beware, not all had them. Some expected the System BIOS
of the PC/AT to incorporate that functionality.

Edit: The two holes on the left end of the card indicate that this was part of a File Card (aka Hard Card),
or that it was prepared for such a use.