This expression has no English equivalent, at least not one that I'm aware of.
It describes the situation where you have a beautiful woman on your right arm and another beautiful woman on your left arm.
I found the literal meaning very nice.
Reading: ryou te ni hana
Meaning: flanked by two beautiful women; two blessings at once
Literally: a flower in both hands (a flower in each hand)
And if the women have flower names (Lilac, Lily, Daisy, Jasmine etc.) then this is a double fun expression!