וַיָּ֣קָם ׀ בַּלַּ֣יְלָה ה֗וּא וַיִּקַּ֞ח אֶת־שְׁתֵּ֤י נָשָׁיו֙ וְאֶת־שְׁתֵּ֣י שִׁפְחֹתָ֔יו וְאֶת־אַחַ֥ד עָשָׂ֖ר יְלָדָ֑יו וַֽיַּעֲבֹ֖ר אֵ֥ת מַעֲבַ֥ר יַבֹּֽק׃
And he arose that night and took his two wives and his two maidservants and his eleven children, and crossed the ford of the Yabbok.
Bereshit Rabbah 76:5 (and related on the eleven children).
Sefaria · Bereshit Rabbah 76:5
ואת אחד עשר ילדיו — ודינה היכן היתה? נתנה בתיבה ונעל בפניה.
“And his eleven children” — and where was Dinah? He placed her in a chest and locked it.
The Midrash accounts for the missing twelfth child by explaining that Dinah was concealed.
Derash on the number eleven (Bereshit Rabbah).
Yaakov hid Dinah so that Eisav would not see her, accounting for the count of eleven.