In the same way, the Spirit too comes to the aid of our weakness; for we do not know how to pray as we ought, but the Spirit itself intercedes with inexpressible groanings. Romans 8:26
Our prayers are sent to God by the Holy Spirit, who intercedes on our behalf. Because of our human nature we do not understand the way of the Spirit. How the Spirit groans in a way we would never understand. It is a language unknown to us, it is directed to God. Because we pray with our lips and with our thoughts, we understand what we pray. We know what we hear and think when we pray.
Have any ever cleansed their heart, received communion, and somehow knew you were groaning. It happens. It's the Spirit groaning your prayers to God. Or saying a prayer and it disappears so fast that you wonder if you even said it. Is it possible and does it happen, yes it does.