The Discovery is outfitted with an experimental “spore drive,” enabling it to travel much faster than other Federation (or Klingon, Romulan etc.) ships. We see its speed in Season 1, Episode 4, in which Discovery is able to rescue a primary dilithium source from an attack by the Klingon Great Houses faster than even nearby ships.
In Lorca’s sales pitch in the previous episode, he makes it sound like the spore drive can transport someone in the blink of an eye, but that might just be hyperbole. Is the spore drive instantaneous, or simply much faster than current Federation warp drives?