I agree with the outlining of the comment above, except for the song isn't about sex. It's more about a boy cherishing his girl's body. "But a field had I found with a small hole in the ground". He is rather referring to her stomach and belly button. This way the ending of the song makes more sense. "I walked past a place, one I cannot say. But when you’re mine, girl I’ll take the journey anytime. Girl I’ll take the journey anytime." He is waiting for marriage, when the girl is truly his. Then he will take the journey anytime. Until then, he can't speak of that place.
I agree with the outlining of the comment above, except for the song isn't about sex. It's more about a boy cherishing his girl's body. "But a field had I found with a small hole in the ground". He is rather referring to her stomach and belly button. This way the ending of the song makes more sense. "I walked past a place, one I cannot say. But when you’re mine, girl I’ll take the journey anytime. Girl I’ll take the journey anytime." He is waiting for marriage, when the girl is truly his. Then he will take the journey anytime. Until then, he can't speak of that place.