The twelve stars, which make up the crown (garland) upon the woman's head in this chapter, represent the 12 tribes of Israel from which the 144,000 of chapter 7 were selected and sealed.
In a sense, Jerusalem is the mother of all the Jewish people. In Matt. 23:37 Jesus said,
" ...O Jerusalem, Jerusalem,... How often I wanted to gather your children together, as a hen gathers her chicks under her wings, but you were not willing."
When He said, "...your children...", Jesus was referring to all the children of Israel, not only the inhabitants of Jerusalem.
"...woman clothed with the sun..."
The light radiating from the woman is being emitted by the holy child within her, of which she is about to give birth (verse 2) and which shall be caught up to "...God and His Throne..." (verse 5); to be presented as the "...firstfruits to God and to the Lamb" (14:4).