White Balsamic Vinegar is not officially a balsamic vinegar.
It is thinner, and a pale gold or amber color. It is less sweet than proper balsamic, having a mellow flavor with a bit of tang at the end.
It is made from must from white grapes, usually Trebbiano grapes and / or Lambrusco grapes, combined with regular white wine vinegar.
The processing of the grapes is designed to avoid coloration happening. When making regular balsamic, the must is caramelized, causing the darker color that it has. That step is omitted in making White Balsamic Vinegar. Instead, the must is cooked slowly under pressure to avoid that happening. And, instead of being aged in charred barrels (as regular balsamic is), White Balsamic Vinegar is aged in uncharred wooden barrels.
It can be aged anywhere from 1 year to 12 years.
The acid level will be around 5.5 to 6 %, pretty much the same as that for most white wine vinegars.
White Balsamic Vinegar is used when you are using it as an ingredient in a dish and don't want the color affected. It is particularly good for pasta salads, because it won't turn the pasta brown, the way regular balsamic vinegar will.
You can also use it with some olive oil as a dipping condiment for bread, or use as you would any white wine vinegar, particularly where you want to let the somewhat better taste come through.