Who Beelzebub is
Beelzebub belongs to the rebel angels who lie defeated in Hell after the war in Heaven. When Satan first stirs on the burning lake, he speaks to Beelzebub as his closest companion.
What Beelzebub wants
At the council in Pandemonium, Beelzebub proposes a way to strike at God through his new creation. He tells the rebels about a new world and mankind, set to take the place the angels lost. His proposal is to seize that world or ruin it, and the council agrees to the plan.
Beelzebub and the others in the story
Beelzebub's speech seems to give voice to Satan's own plan, linking their alliance with the way the council is steered. Other speakers urge open war, waiting, or making a home in Hell, but his proposal directs their attention elsewhere. When someone must undertake the dangerous journey alone, Satan volunteers to carry the agreed plan forward.
Questions
Who is Beelzebub in Paradise Lost?
Beelzebub is a fallen angel and Satan's closest companion in Hell.
What does Beelzebub propose at the council?
He proposes attacking God's new creation by seizing or ruining the world where mankind lives.
How is Beelzebub connected to Satan?
He is Satan's closest ally, and his council speech appears to present Satan's own strategy.