Read the full text of Henry VIII Prologue with a side-by-side translation HERE.
Someone steps out on the stage and delivers a speech. Who is this mysterious figure? The truth is: we're not sure. Some scholars call him the "Chorus," while others stick with the super original name "Prologue" (since he reads the prologue).
Whatever his name, he comes out on stage and gives us in the audience the 411 on what they're about to see.
The Prologue mentions a couple of important themes in the play like pity and truth. He also sets the genre straight for us: it's not a comedy we're about to see, so there'll be no crude jokes ("merry bawdy") or slapstick ("noise of targets") anywhere to be found. If you're looking for laughter, this isn't the play for you; it's full of serious stuff.
So what can we expect? Well, this play is part serious, part thriller, and all politics.
And one last thing, the Prologue tells us: make sure to think of the characters as humans. Yes, yes, we know they're actors playing parts, but let's pretend that they're alive and real. That will make the whole play way more interesting. Agreed?