A ‘combo’ is a combat technique which requires a combination of commands.
When you type ‘r?’, you’ll see the combat table for your right hand. The first line lists your valid (one-letter) commands, followed in brackets by their cost in AP (see ‘help actions’). The second line lists the definitions of what each one-letter command stands for (for example ‘e’ might stand for ‘elbow’). Below that is a separator line, followed by your techniques (including combos).
Suppose you see a ‘pfs’ combo in the combat table for your right hand. Looking at the top of your table you see ‘p (50)’ above the definition ‘palm’, ‘f (50)’ above the definition ‘fist’, and ‘s (100)’ above the definition ‘strike’. That means that you can perform the ‘pfs’ combo with your right hand by typing ‘rp’, ‘rf’, ‘rs’ (which literally means right palm, right fist, right strike).
The same approach is used for spells. If you have an ‘energy bolt’ spell which uses the ‘sp’ combo, you can cast it right-handed by typing ‘rs’, ‘rp’ (meaning right snap, right point), or left-handed by typing ‘ls’, ‘lp’. Don’t forget to type ‘r? info’ to see the names of your spells.
See also: tutorial interleaving counter-attack techniques