The fornicator shall not marry any but a fornicatoress or a polytheist, and likewise to a fornicatoress, none shall marry her but a fornicator or a polytheist: such marriages are forbidden to the believers.
Meaning:-
Fornicator: a person who has sex with someone who they are not married.
Fornication:voluntary sexual intercourse between two unmarried persons or two persons not married to each other.
Polytheist: belief in more than one god or in many gods.