The standard connection cable supplied with Uniden scanners is for use with 9 pin serial ports, and most if not all "new" computers made in the past 2 years or so don't even have those types of old ports anymore. Uniden sells an actual USB connection cable, I think it retails for another $30 or so.
The other options are:
- get a PCI serial port card that provides you with 1 or 2 9-pin serial ports for such purposes, or...
- get a cable similar to the one you just mentioned. I have one made by Keyspan that I've been using for years now, it works great without issues as long as the drivers are available so the operating system can talk to the device (luckily, Keyspan is great with those for Windows).
The USB-to-Serial cables come in a variety of shapes, forms, and sizes but as long as it's providing a 9 pin male end for the Uniden serial cable to attach to (that's the cable that came with your scanner) you should be good to go.
RS-232 is just the "iindustry" nomenclature/name for such ports, and you can have 9 pin, 25 pin, 50 pin, etc. When people say "serial port" in reference to computers, pretty much everyone knows it means the 9-pin serial port you're looking for that doesn't exist on your PC, much the same as "printer port" translates to parallel port (the wider 25 pin ports). Believe it or not, they all provide the same functionality - there are adapters that would let you go from a 25 pin parallel port and match that 9-pin female end of the connection cable, but just as serial ports are disappearing from PCs, so are the parallel ports.
Most everything is moving to USB which is smaller, more common, and the way things are done nowadays.
Good luck...