The neck of the guitar adjoins the "body" of the instrument. The body of the guitar will vary greatly from guitar to guitar. Most acoustic and classical guitars have a hollowed out body, and a "sound hole," designed to project the sound of the guitar. Most electric guitars have a solid body, and thus will not have a sound hole. Electric guitars will instead have "pick-ups" where the soundhole is located. These "pick-ups" are essentially small microphones, which allow the capture the sound of the ringing strings, allowing them to be amplified.
Of course, this top-down lecturing is all very abstract without examples. Let me give you the worst case scenario. My school talent show, 2008. Two friends of mine performED an ambitious but utterly inappropriate Metallica cover in front of the other students, their parents and the faculty. It was excruciating. Although the solos (presumably the only thing they had bothered to practice) were technically flawless, the whole song was undone by their terrible rhythm. The timing of the song became displaced, the chords were so badly fingered that it was difficult to hear the riff and consequently the whole performance fell apart. They looked like morons. They had sacrificed learning basic rhythm and paid the price. Make sure you don’t do the same.