Tone is the electric guitar's sound. Electric guitarists talk about tone alot. Tone is a mystical thing that is constantly being tweaked and improved upon but never achieved. But here's the items that create tone in the order of importance.
The amp is an electric guitar's soundhole. If your amp has a weedy speaker then no matter how good your guitar it will sound weedy. Same applies to electronics if your amp is engineered to give a hi-gain metal sound then you will be working against it's character trying for a warm bluesy tone.
Pickups determine an electric guitar's sound. There are two basic types; single coil and humbuckers. Humbuckers use a double coil that cancels out noise from computers, neon bar-signs etc. Humbuckers sound warm and solid, perfect for rhythmn guitar work. Single coils have no such refinement, their screaming tone is great for lead guitar. However there's no hard and fast divide. Some lead guitarist play humbuckers. Indeed you can mix and match the two types. Two single coils at the neck and a humbucker at the bridge pickup poition is a common combination.
Not all pickups are equal. A quality pickup makes for good tone and usually influences a guitar's price.
An electric guitar has wiring hidden away under a plate at the back or under the scratchplate. The precise wiring of the volume, tone and pickup position controls can make a huge difference to how an electric guitar sound. A 'retro' series guitar wired to be authentic to a historical era may sound right but deliver alot less than a modern one designed with up-to-date electrics.
Many electric guitarists obsess over the type of wood used and claim to be able to tell the difference. Some very low end electric guitar's have plywood bodies and these are certainly poor but once a heavy wood is used the precise variety isn't vital. The body anchors the pickups and bridge. If the body wood isn't up to it these will vibrate in a bad way. Likewise the body neck joint must be tight or tone is affected.
Where the strings go after the first fret and on to the tuners. If the string does not move smoothly over the nut the guitar will appear difficult to tune. Graphite between nut and string can really help.
Some claim that the nitro-cellulose finish restricts a guitar and that only a natural unpainted guitar will give good tone. The effect of finish is tiny if present at all and most guitarists love a sunburst finish without ever suffering loss of tone.