Your keyboard offers a (quasi-) stereo pair of RCA output jacks marked Audio Out R and L.
We now have to consider what inputs your computer has. If you have an audio interface with dedicated Line In L and Line In R sockets, use a pair of cables with the appropriate connectors - probably either RCA - RCA or RCA - 1/4" jack plug. (But if you had one of those, I don't think you'd be asking this question!)
Quite likely, on a reasonably modern computer. you have a multipurpose stereo 1/8" jack socket. When a connection is made, the computer asks you what has just been connected. Use a cable with a 'stereo minijack' on one end, a split to two RCA jacks on the other. This very common item is sometimes called a 'soundcard cable'.
It's unlikely that the computer has any sort of input level control, so it's your job to make sure the signal doesn't overload the input.
If you hit problems - typically a loud hum while recording, consider just pointing a domestic recording device at the instrument's speakers. Results from today's smartphones and tablets are really surprisingly good.