I just met a girl and we had a good conversation. She sent a message when she got home and said, "Single to be liberated." What does this mean? Is it a hint to me?

She just expressed her feelings, which means that she is still attractive because she can attract you. Whether you can develop further depends on your performance. Now you can confess to her, so that you can be attracted to her. She truly feels liberated by being single, but it won’t work if it’s too late and the feeling passes.