Targum Onkelos and Targum Yonasan: It implies a girl who is not betrothed.

Kesuvos, 38a: It implies "Na'arah" - 've'Lo Bogeres'; "Besulah" - 've'Lo Be'ulah' - If the girl is a Bogeres or a Be'ula ¹ (not a virgin) or married, the rapist is precluded from the Dinim mentioned in the Pasuk.

Kesuvos, 38a: It implies that, if the Na'arah became divorced after the betrothal, the K'nas goes to her and not to her father. ¹

Kesuvos, 38a #2: We learn via a Gezeirah Shavah "Asher Lo Orasah" "Asher Lo Orasah" from Mefutah - in Mishpatim, Sh'mos, 22:15, that, just as there, he pays Shekalim, so too, here, and that, just as here he pays fifty Shekalim, so too there there.