In order to hear your guitar you're going to need an amplifier, which is going to take the signal from your pickups and make it nice and loud.
There are a few different types of amp which you'll no doubt have seen bands playing. First up, there are different amps suitable for guitars, bass guitars and acoustic guitars, so make sure you're picking up the right sort from the off.
When you're looking at amps, you'll see two distinct types: combos, which are compact all-in-one unites, and larger amplifiers consisting of a separate head and cab, sometimes referred to as 'stacks'.
Which one you go for will ultimately depend on how much noise you want to make, with combos more common for home and smaller bands, and stacks preferred by guitarists who want to make a lot of noise.
These rules aren't hard and fast - some larger combos are used by bands playing the bigger stages, for instance. Generally, most beginners starts with a smaller combo though.
Aside from these external differences, there are also internal considerations to think about. There are basically three different sorts of amplifier in terms of how they achieve the sound.
Solid-state amps tend to be more affordable, and better suited to producing cleaner - ie: not distorted - sounds.
Valve or tube amps use vacuum tubes, and are generally thought to produce a warmer sound that is more pleasing to a lot of players' ears.
Finally there are modelling amps, which use digital technology to emulate the sound of well-known amplifiers, giving you access to approximations of their tones at a fraction of the price.