My son got no pedals of FX and i don't even know what's a FX 

What can a FX do and how much?
I think its Metal (coz i can't stand the music he listen in his room). He bought a Red Hot Chili Pepper CD and Metallica T-Shirt and Badge while in SG.
noted above comments, thanks
noted above comments, thanks

Went to CK Music today and they were closed      Anyway went to Bentley and they got no Marshall 30/50W Amp for below RM2K. Saw the Roland Cube-30 (RM900) which my son said his friend got and he had heard the thing before. Also saw GT8 - looks cool but have no idea what it does besides it being able to plug into the computer.

Here my son's AX-50 (pic taken with my Dopod 818 Pro)

A guitarist just doesn't rely on his amp and guitar alone to come up with sounds. He usually adds effects pedals or units to enhance the tone.

Most popular individual effect pedals will be overdrives/distortion units and a Wah pedal. Then there are delay effects, echo, reverb, looping, chorus, phaser...... the list will go on and on and on. Again, these are put in between the amplifier and guitar signal chain to provide some awsome effects.

Like Nerd says, the GT-8 is an excellent example of what a multi-fx is. From that one unit, you are able to get the sounds from a whole bunch of single pedals and put them together in a single contained unit.

Since he already has 5 guitars, get him a multi-fx pedal next so he can play around with different effects before setteling on his own unique sound. The Zoom G2.1u is getting rave reviews in this forum because it's cheap, has average effects, an expression pedal (used to control Wah effects or the volume) and also has the added bonus of allowing you to record directly to the PC via USB. More info on the pedal can be found here: http://www.zoom.co.jp/english/products/g21u/index.php

And since your son is into metal, I strongly suggest getting him a Wah pedal as well (yes, even though a multi-fx unit has a wah effect, it's best to get this on it's own). Wah effect is kind of like how the teacher in the Peanuts cartoon talks......The most popular brand of Wah's is from Dunlop and they produce killer Wahs. I suggest getting the GCB-90 wah if you're on a budget, but if you have a little bit more extra..... get him either the Crybaby from hell (Dimebag's signature Wah) or Slash's Signature wah...... both of them EXCELLENT Metal wahs.

Speaking of multi-fx........ my next effect pedal will be either the Vox Tonelab SE or the Zoom G9.2tt........ both using a tube pre-amp..... YUMMY!

my college wants to purchase music instruments: they gave a budget of RM5000 and ask us to get:

1. a drum set
2. a bass
3. a bass amp
4. a guitar amp

can be second hand, but must be quality stuff.
please offer suggestions!