Ping, or latency, is time.
On the internet, you can get high bandwidth (megabytes per second) with high ping times (how many milliseconds, or thousandths of a second, it takes for information to travel between you and the server you're contacting).
So long as your ping is under about 100ms, you'll never be able to tell the difference. Some technologies have much higher latency, or ping, times. Dialup can have between 200-300ms. Satellite internet can have over 400 sometimes.
But for regular web browsing you'll never tell. Its in videogames and certain applications where getting an absolutely minimal ping is key, as the time it takes for information to get back and forth can be life or death.
Also ping depends on the servers you're contacting. Try running a speed test of an Australian server, it'll probably ping over 300ms.
Ping is how long it takes for something to get from "A" to "B". Your bandwidth is how much you can send within a time frame between "A" and "B".