Thank you for your time. Revelations 5 v 6 - Who/what are the 7 spirits of God sent to Earth?

I'm not trying to understand whole of Revelations - which really would be impossible, but I would like to have a interpretation to this, which appears logical. Looked on the web and the common view is that 7 is a number meaning "fullness" and it refers to Holy Spirit, but the Holy Spirit is accessible to us in it's fullness already. Any other idea?