What does this mean hands of Hashem? , the voice of Hashem? how to understand it?

Obviously, God doesn't have hands, but it's referring symbolically to His actions. Similarly, to "heed the voice of God", is to listen to His Torah, commandments and prophets. Just at the giving of the Ten Commandments at Mt. Sinai where God wanted to "reveal Himself", as if it were, so as to introduce Himself to Israel, so there it's meant to be taken literally, that over 2 million Jews miraculously heard Him.