The majority of acoustic and electric guitars are fabricated from wood. Instrument tolerances change with temperature and humidity, potentially requiring seasonal adjustment.
New instruments are not set up when leaving the factory. The guitar will probably be stored in a warehouse and shipped thousands of miles in varying conditions before being hung up in a shop, with a set of strings that may not suit you. To achieve the best performance from this guitar, adjustment will be necessary.
The most common set up request is to lower the action, which reduces the height of the strings over the fingerboard. This can make any instrument much more “playable”, particularly for a beginner and can vastly improve a budget guitar.
A standard electric set up will assess the instrument for any faults and includes a restring and adjusting string action, truss rod, intonation, top nut and pickup heights. A fret clean, lubrication and cleaning of pots and switches if needed. Fretwork is not included. Acoustic set-ups follow a similar procedure.