Acoustic guitars come in shapes and sizes, but every one of them works the same way. Strings vibrate. The soundhole projects. Wood resonates. No electronics required.
The five parts that matter
Soundhole. The round hole in the body. Resists the temptation to play into it; play over it, with your strumming hand floating above the soundhole, not through it.
Top (soundboard). The flat front of the body. Spruce or cedar most of the time. This piece does 90% of the sound projection. Drop your guitar and bring it to a luthier; bend the top and your tone is permanently changed.
Neck and frets. Same as electric. EADGBe tuning, 12 frets to the body junction, usually 6 more accessible above.
Bridge and saddle. Where strings anchor at the body. The saddle (the small piece embedded in the bridge) sets your string height. Higher saddle = higher action = louder but harder to fret.
Body shape. Dreadnought (biggest, loudest, country / strummed rock), concert (mid-sized, balanced, fingerstyle), parlor (small, warm, blues). If you have whatever is in front of you, it works fine for now.
Try it
Hold the guitar. Strum all six strings open. Listen to how long the note rings. That sustain is what makes an acoustic so forgiving: even a sloppy chord change leaves the previous chord ringing while the next one starts.Next: tuning. Same EADGBe as electric, but acoustics drift more from temperature.