Summarily just means you can deal with it in the mag court without a jury. It's your choice. It's just as serious however it'll be cheaper if you use a lawyer.
You can always negotiate. Once you have the BOE you can just accept that you're going to lose and indicate you'll plead guilty and happy for it to be heard summarily and then a magistrate will handle it without a trial. You can obviously go not guilty and either have a jury in district court (I assume) or you can go back to Pros and tell them you'll plead guilty to a lesser charge (criminal damage).
I'm assuming Victoria has a formal case conferencing process.
What on earth did you do that caused them to charge you for burning what appears to be an abandoned pallet? If it's abandoned it is not owned by anyone.