What does 1 Samuel 1:6 mean?

Polygamy was common in Israel during this era (1 Samuel 1:1–2), but popularity does not make something right, or easy. Sarah gave her servant Hagar to Abraham to bear children on her behalf. After Hagar conceived, she looked with contempt on Sarah, and Sarah came to resent Hagar and treated her harshly (Genesis 16:1–6). Rachel desperately envied her sister for giving Jacob children while she could not. She even named one of her surrogate children something like "mighty wrestlings" because of her intense rivalry with her sister (Genesis 30:1–8). Of course, deep resentment also comes when one wife is more favored by the husband. That was very much the case with Jacob, Rachel, and Leah (Genesis 29:30–31).

In this case, Peninnah is remembered only as the adversary or even tormentor of Hannah. Hannah cannot have children (1 Samuel 1:2, 5). Elkanah's second wife may have given him sons, but she apparently couldn't steal his heart from Hannah (1 Samuel 1:5). She would have noticed Elkanah giving Hannah the double portion of the meat at the festival. Perhaps as a response to favoritism (Genesis 37:3–4), Peninnah was cruel about Hannah's infertility. She might have constantly provoked Hannah to irritate her. Or she may have been especially spiteful. She became Hannah's tormentor, exploiting her grief to cause her more pain.

Here, again, the text emphasizes that God had prevented Hannah from conceiving. Even without direct divine intervention, infertility is hardly rare. Neither Hannah nor Elkanah is said to be responsible in any way for their childlessness (John 9:1–3).