# I compare you, my love, to a mare among Pharaoh's chariot horses
"My love, you are as beautiful as any of Pharaoh's chariot horses". The Jews of those days considered horses beautiful, and the Pharaoh's horses would have been the most beautiful he could find.
# my love
"you whom I love"
# Pharaoh's chariot horses
"the horses that pull Pharaoh's chariots"