Hi and welcome to the forum!
Good question, so ebike batteries are rated with a nominal voltage.
So your battery is made up of individual cells which each charge up to a maximum of 4.2V.
So a 48V battery with 13 cells should only charge to 4.2V x 13 = 54.6V
For reference a 52V battery has 14 cells and will charge up to 4.2V x 14 = 58.8V
In saying all that, lithium batteries tolerate an overcharge and so it's quite possible your 48V battery is charging up to 58.8V. However, this is only a surface charge and you'll notice it will quickly drop a couple of volts by the time you reach the end of your driveway.
If it doesn't drop down in voltage a couple of volts very quickly, then you might actually have a 52V battery instead.