What does Judges 13:4 mean?

Manoah's barren wife has just received enormously good news. This came directly from "the angel of the LORD," likely meaning a visible presence of God Himself. She was told to expect to bear a son. That news is immediately followed by instructions about how to raise that son. This promise from God comes with rules; this child will not be an ordinary boy.

The following verse refers to the Nazirite vow (Judges 13:5). The woman's son is to live an extreme version of that lifestyle (Numbers 6:1–21). Nazarite refers to "one separated" or "one consecrated." An Israelite volunteering to live as a Nazarite would not drink alcohol or eat any foods that were unclean, according to the law, during the time of their vow. Treating a child, let alone an unborn infant, as a Nazirite is extremely unusual. To keep her unborn child from violating the vow, Manoah's wife will have to abstain from certain things until the baby is born.