Jamieson, Fausset and Brown on Song of Solomon 7:5

5. upon thee--the headdress "upon" her.

Carmel--signifying a well-cultivated field (Is 35:2). In So 5:15 He is compared to majestic Lebanon; she here, to fruitful Carmel. Her headdress, or crown (2Ti 4:8; 1Pe 5:4). Also the souls won by her (1Th 2:19, 20), a token of her fruitfulness.

purple--royalty (Re 1:6). As applied to hair, it expresses the glossy splendor of black hair (literally, "pendulous hair") so much admired in the East (So 4:1). While the King compares her hair to the flowering hair of goats (the token of her subjection), the daughters of Jerusalem compare it to royal purple.

galleries--(so So 1:17, Margin; Re 21:3). But Maurer translates here, "flowing ringlets"; with these, as with "thongs" (so Lee, from the Arabic translates it) "the King is held" bound (So 6:5; Pr 6:25). Her purple crowns of martyrdom especially captivated the King, appearing from His galleries (Ac 7:55, 56). As Samson's strength was in his locks (Jud 16:17). Here first the daughters see the King themselves.