Looks like a field maple but this hybrid Norwegian Maple has better autumn colour. They grow fast. I am developing a Japanese style stroll garden and have about 90 acers, mostly various palmatums. Whenever possible you need to avoid letting tight forks occur and prune early on to a single leader.
This might be OK for you, or it might gradually show an ugly and large scar, which may turn white. If you wish this to be a key specimen tree for the long term, then I would whip this one out and replace it. That is in fact what I would do. It will never be a great specimen in this condition. If it is just "a tree" then I would wait and see if it gets worse. It will not get better.
When you get divisions like this in young stock, sometimes you can wedge them and divide them with wire if you do not wish to prune away a close divided stem. Bonsai or Niwaki methodology. However, far too late for this here. I would expect this type of tree to grow to a maximum of 30 feet. Generally that is too big for most gardens and I would be constraining it already based on the photo of your garden, if you decide to keep it. Prune when dormant (winter) after leaf drop, but take photos now of the shape you want to prune to, if you decide to keep it.
