Exodus 21:7

if a man sell his daughter as he easily might do, either from actual poverty, or because he was in such circumstances that it would be more advantageous for his daughter to be the concubine of a well-to-do neighbour than to marry a man in her own social position.

maidservant better, bondwoman (RVm.), or female slave: -maid-servant" has associations which are not at all those of ancient Hebrew society. Here the word ("âmâh) denotes in particular a female slave bought not only to do household work, but also to be her master's concubine. Cf. the same word in Genesis 21:10 ff. (of Hagar), Judges 9:18 (of Gideon's concubine; see Exodus 8:31), Exodus 19:19.

as the male slaves do v.2.