It can be both. Technically "a couple of" is two, but can refer to a small amount or a few. If you are unsure about your use of "a couple of" for more than two things, you can always say "a few" instead.

Strictly it means two. A married couple, for example, is two people. But people sometimes use it when they really mean 'a few'.

It is annoyingly ambiguous. When I am at work and a customer requests "a couple of" something, I have to ask whether they literally mean two, because sometimes they want more than two. I avoid using the expression when the exact amount is important. When I say it, I mean "about two to five, it doesn't matter how many". For instance: "I wondered if anybody was home, so I knocked on the door a couple times." It doesn't matter exactly how many times I knocked, just that there was some brief knocking.

two