I’ve actually had this very problem of having a too-hard butter for my bread just yesterday, here’s a simple way to soften your butter very quickly using a roller.
The best thing to do to soften your butter is to put it out on the kitchen counter for an hour before you have to use it. But sometimes we don’t think that far ahead. One popular solution is to put the cold butter in the microwave for 10 to 20 seconds. The problem with microwaving butter is that the microwave can heat the butter unevenly, and tends to over-soften or even melt the butter in places. You want pliable butter for beating, not almost melting butter.