Guitars are transposing instruments. Does this mean if the music notation is calling for a C4 I should play a C3? Or would I still play a C4? Does the original instrument the notation was made for matter?
Guitar notation is written in treble clef, an octave above the sounding pitch. So if you want to hear C3 from a guitar, write C4.
When guitarists read a guitar part, they don't have to do any transposing. The note they see, played the way they have learned to play it, will deliver the required result.
If guitarists are reading music written for some OTHER instrument (piano, perhaps) they will have to play what THEY call C4 to get what a pianist calls C3. But, mostly, they needn't bother. It will sound fine in the 'wrong' octave.
Guitar music appears to be written an octave higher than it sounds.
It signifies that actually, the music is in the right octave for guitar, just written on the treble clef 'an octave too high', for convenience - of both writing and reading. To write music for guitar in its proper octave, it would need a clef of its own - hardly practical.
In order to play any other music not written specifically for guitar, it would need to play those dots an octave higher.