I currently have 8gb of RAM in my pc & I was considering upgrading to 32gb because of the available slots & cost.
How will this affect audio and/or video production?

How will it affect production?  VERY WELL!
 
I have 16 Gb in my PC, and have yet to bog it down.  :)

Does anyone know technically what more ram does?

Really depends on how much you use sample based instruments, what OS are you running also will the Bios of your MoBo support 32gig.

bilo06
I currently have 8gb of RAM in my pc & I was considering upgrading to 32gb because of the available slots & cost.
How will this affect audio and/or video production?

It deepends on several conditions:
Which Ram format : DDR 3 1600 mhz ?
Are you running a lot of samples ,Vst fx and  instruments ?
How moch tracks.?
Which Cpu ?
Onboard shared video memory ? aso.
Basicely 8 or 16 gb Ram are enough if you are not running
very big projects.
 

Go to http://www.userbenchmark.com and click on "free download" and then install the program and benchtest your current computer, then select the replacement RAM you want to get and it will tell you exactly what kind of performance increases you can expect.  You will be surprised about RAM.  While more ram is better for loading large amounts samples into your project, RAM appears to vary in speed with each 8gb cluster (at least it does with my motherboard).  I don't know if this is such a bad thing for video or audio but it is a very valuable site and I used it extensively when choosing what to uprgade on my system.

I have 16 GB Ram(DDR 3, 1333 mhz) and some big projects running
(AD drums, 3-4 synths, 60 or more tracks ) running smoothly,
sometimes I  use the freeze button or bouince the vst instruments,
to ensure that the project isn´t overloaded.

My specs are:
8gb of DDR3 1600 RAM
Intel Zeon quadcore
Windows 7 Pro
Line 6 Toneport GX audio/guitar interface

I just upgraded from 8GB to 32GB, and although more than 8GB is recommended, unless you are running something intensive, 16GB should be sufficient. 32GB is extreme overkill for me, but DDR3 is getting cheap.

Also check your MB to see what speed it will support. I moved from 1600 to 2133 (max supported with XMP profile 2).

I assume you're on a 64 bit version of windows and using the 64 bit Sonar.  If you are running only 32 bit, memory can only be paged in 4GB at a time, creating a bottleneck if you have a lot of RAM and working on a large project.