Before I get into this, this needs said - If this can be done with an Adruino or Raspberry Pi, just do it that way. So much easier. Arduino can plug in via USB and you’re done. RPi is a computer already.
Alright so this could be / kind of is a bigger topic. All VEX brains can communicate with a PC it’s just a matter of how much work you want to take on and what you are trying to accomplish.
There are different ways to do it as well. In general these break down to Serial, UART, SPI, I2C, etc. If these terms aren’t familiar to you, you should go learn about communications protocols in embedded systems and come back. Sparkfun has some excellent guides on these subjects.
One easy way is with an FTDI board. It will let you connect a Cortex to PC with a USB cable and four connections. I used to have a detailed post on exactly this subject but it’s probably gone. Actually it’s kind of still there: Cody's BeagleBone Black / Cortex Bridge
I have the images from that guide saved on my vault store, I can grab those for you upon request.
Tabor is talking about a UART to Bluetooth adaptor, and yes these things are cheap and work reasonable well if wireless communications are what you want and the bandwidth and distance limitations of Bluetooth work for you. Other options for wireless communications also include Xbee and Zigbee which range in distance / bandwidth.
In those options you would leverage the exposed UART on the Cortex (no idea about V5) and plug them into the RX and TX ports of whatever bridge you’re using.
Once communicating, you have the additional problem of HOW to communicate. I don’t mean like… how to send data, I mean how you structure that data, which get’s complicated fast. In general what you are asking for is a generic remote procedure call (RPC) framework where the VEX brain is the “master” and the PC is “slave”. I apologize for the somewhat offensive terms, as I am fully aware of the traditional problems with those terms, nonetheless this is what the computer science community has used to describe this relationship for decades so I will just use my industries terms and hopefully that’s OK with all the super mature moderators we have here on VF who can clearly differentiate between real bigotry and realism. 
Anyway creating this RPC exchange is a little tricky. You have to write code that runs on both the VEX brain and the PC on either end of a serial link. This is because regardless of how you send the data over to the PC, it will show up to the PC (and Cortex) as a serial connection. Those BT bridges go from VEX Brain (as serial) > UART > BT > PC (as serial), as do the FTDI boards VEX Brain (as serial) > UART > PC (as serial).
So you write a program on the Cortex (or whatever) that sends a command message, the PC program gets it and responds with a payload, the Cortex reads the payload and does something with it.
Not that bad. For a very dumb version of this you can send getTheThing\r\n to the PC, and send back [PAYLOAD]\r\n and as long as the payload never naturally contains a newline char, you’re good to go.
To be clear, no existing nice RPC framework exists, you have to write it. VEX does not run Grbl or whatever (if you are thinking of doing numeric control).
