What does Judges 13:18 mean?

This is one part of an extraordinary conversation. Manoah seems to believe the "man" to whom he speaks is an extraordinary human being, perhaps a prophet of God (Judges 13:8–11). He is convinced the man's message is true: that he and his wife will have a special son together (Judges 13:2–7). He has offered the stranger a meal, which has been declined, and has now asked the stranger His name so that they can honor Him when their son is born (Judges 13:12–17).

The "man" does not give a name, and likely for a good reason. When Moses heard from God, out of a burning bush, the Lord identified Himself (Exodus 3:14). In that encounter, God did not give a personal name, but used the expression e'heyeh aser' e'heyeh, literally "I am who I am." Now, Manoah and his wife are speaking with "the angel of the LORD," almost certainly God Himself in some temporary form. When asked to identify Himself (Judges 13:17), no name is given. In fact, the name of this Being is beyond their comprehension (Isaiah 55:8–9).

Scripture doesn't indicate if Manoah is catching on to the true, otherworldly identity of this stranger. If he does not realize this, yet, he will very soon (Judges 13:20–21).