It's usually not -a- needle, but a cluster of very small needles in the gun (ranging anywhere from 2-14 typically, depending on the kind of tattoo you're getting and the detail involved....the more detail, the fewer needles).  What do they feel like?  Hard to explain.  Sort of like scratching a sunburn.  If you take the tip of a knife, and drag it across your skin - not enough to break the skin, just to leave a white scratch - that is what it feels like.  It's not bad at all.  I am a total wimp when it comes to pain, and I handle tattoo's just fine.  If you are REALLY concerned with the pain factor, consider having one done on your upper arm.  That is the least painful place to be inked.  I doubt you would have a problem at all, though.
Mimi 😀