The rocket just hit "MECO" – or main engine cutoff. That means the 9 Merlin engines attached to the rocket's first-stage, the ones that give the initial thrust at liftoff, are done burning fuel for now.
The first-stage of the rocket then broke off from the second-stage rocket, which has its own massive engine optimized for blasting through space where the atmosphere is super thin.
The second-stage lit its engine, and it's now powering the Crew Dragon capsule to higher and higher speed.
It'll need to hit at least 17,000 miles per hour to reach "orbital velocity." That essentially means the spacecraft will be traveling so fast, at just the right angle, that it'll begin to continuously fall around the earth — otherwise known as orbiting.