That motor is almost certainly sold in multiple versions, for which the primary (likely only) difference is the specific speed they will reach on a given voltage, the KV Hoggdoc referenced above.
It might be 20mph. It might be 25mph. It might be 30 mph. If it is too slow for you, you can either get a higher voltage battery, and a higher voltage controller, which is going to get expensive. OR, what I would recommend because it is FAR, FAR cheaper, is to get the high-speed motor in the first place. Note that the high-speed motor will require a LOT more amps for acceleration and hill climbing, this is where the controller may limit you, more amps means more Fets and more Fets means more cash, also may need cooling if climbing for more than a few minutes, the low-speed motor will use less amps for acceleration or hill climbing, but will need more volts for more speed.
is this by any chance a brushed motor with a short chain drive to the rear, like the old Curie ebikes? Not a hub motor? If so, those are completely different. Fairly reliable, but they do NOT like higher than designed voltages, unlike a DD Hub.