What is the prologue of a book and how long is it supposed to be? Can it be 1-2 paragraphs long?
It can be any length you want. Make sure it sets up your story so that the reader wants to read more.
A prologue (at least in the writing sense) is an introduction to the story or piece you are writing.
In terms of length, it should be as long as you need it to be to get the background or facts across you need the reader to know for the story to make sense. But it should be short enough so as to not become part of the story - this is only for background or introductory information, not to be a story within the story.
As an example, if I was to write a story about Bob's last days on earth, I could do it this way:
Prologue: "Bob's last thought as he slipped into the longest sleep he would ever have was gratitude for friends and family who had allowed him to make up for lost time."
Story: The story starts with Bob finding out he is dying, his regrets, his decision to live life to the fullest and die fulfilled, and the relationships formed and/or remade to make that happen.
Epilogue: Short bits on some of the main friends/family who had helped Bob in his quest to die happy.
So in the above example, I can literally do a 1-sentence prologue.
I can also write a story that is sci-fi/fantasy that is about a world where, say... colour is the underlying fabric of magic, and write it from the perspective of someone who has lived in that world their whole life so that they know the rules, the foundations, of that civilization and that world. So you'd need to have a fairly long prologue to get the reader up to speed on what they need to know to have the story make sense. (In contrast, I could write it from the point of view of someone from this world who is first discovering that world and the story would involve learning the rules and ways of magic).
There are also stories where a prologue gives an overshot of the story's world in general and sets up the problem/crisis/reason why this story is going to be interesting, and then the story itself is how the characters find out about said problem and how they deal with it. Those types of prologues end up being a chapter unto themselves and so can be pages long.
Bottom line - don't worry about the length of the prologue. Do concern yourself with making sure it sets up your story in the way you want it to. Will your reader be interested in reading more of your story?
Good luck with the writing!