Several times; once or twice — indicates that something happened a number of times (not many).
私は何度か日本に行ったことがあります。
I have been to Japan several times.
彼に何度か電話したが、出なかった。
I called him several times, but he didn't answer.
その店には何度か行ったことがある。
I've been to that shop a few times.