The Guitar Frets are the spaces between the metal fret wires that run up the guitar fretboard. The space nearest the tuning pegs is Fret 1. After Fret 1, we have Fret 2, followed by Fret 3, Fret 4, Fret 5 and so on.
If you look at the top of the guitar neck, you should see a few dots. These dots help you locate the frets quickly and efficiently.
As a general rule, guitars have a single dot on frets 3, 5, 7, 9 and a double dot on fret 12. You need to memorise which fret each dot falls over so that you can quickly find any fret number that you need to play.