Complex sentence: According to, the angels who sound these trumpets, recieved them after the breaking of the seventh seal, used to secure the apocalyptic document, that was in the right hand of "Him" who sits on the main throne.
Split into simpler sentences: According to, the angels sound these trumpets after the breaking of the seventh seal. These seals secured the apocalyptic document, that was in the right hand of "Him" who sits on the main throne.