Fret buzz is probably the thing guitarists put up with more than anything else. That low rattle or choke when you fret a note, usually worse on certain strings or certain parts of the neck. Nine times out of ten it is not a sign the guitar is broken. It is a sign it needs setting up properly.
The neck is not straight
Guitar necks are not supposed to be perfectly flat. They need a small amount of forward bow (called relief) to give the strings room to vibrate without hitting the frets. If the neck is too flat or back-bowed, the strings catch on the frets and buzz. This is fixed by adjusting the truss rod, which runs through the inside of the neck. Done correctly, it takes a few minutes. Done wrong, you can crack a neck. Go slow, or get someone who knows what they are doing to handle it.
The action is too low
Action is the height of the strings above the frets. Lower action generally makes a guitar easier to play. But if it is set too low, the strings do not have enough clearance and they buzz. The fix is raising the saddles at the bridge. It needs to be done by ear and by feel, not just by following a spec sheet.
The nut is cut too deep
The nut is the small slotted piece at the headstock end of the neck. If the slots are cut too deep, the open strings sit too low and buzz against the first fret. This is a surprisingly common factory defect, even on guitars that cost decent money. It can sometimes be shimmed, but often the nut just needs replacing.
Loose hardware
Sometimes the buzz is not the strings at all. It is a loose machine head, a vibrating truss rod cover, or a strap button that rattles. Worth checking before you assume the worst.
What to do about it
Bring it in. I will have a look at what is causing it and tell you what it will cost to fix before anything gets touched. Sometimes it is a quick adjustment. Sometimes it is more involved. Either way you will know upfront. I am based in Sittingbourne, Kent, and work on electric guitars across Kent and Medway. Drop me a message here.