When we talk about velocity, it always is velocity with respect to Earth.
We are the observers, and we must realise that we ourselves are moving
through inter-galactic space with an amazing speed.
Due to the rotation of the Earth
we are moving around with a linear speed
of almost 0.5 km/s at the equator
(and in New Zealand at about 0.3 km/s)
with respect to the Earth’s axis.
Image from www.josleys.com (edited)
Due to the annual orbit around the Sun
we move with a linear speed of about 30 km/s
with respect to the Sun.
Image from www. earthandsuninorbit.com (edited)
Our Solar system rotates in our galaxy the Milky Way,
with a linear speed of about 220 km/s with respect to the galactic centre.
Image from io.uwinnipeg.ca (edited)
The whole Milky Way galaxy is moving through space with an estimated 300 km/s, although that depends on with respect to what objects we measure that.
Image from www.pureinsight.org (edited)
Anyway, it is important to note that in a Universe where everything moves,
you have to be specific with respect to what objects you measure velocity.
For us here on Earth, that is always with respect to our planet.