dear chocolate, first of all , welcome to Real Faeries!
I've also had a similar experience as you have. There are the Sidhe who are Faery and Nature Guardians– and they are adult sized Beings. Some here have had experiences with them or have seen them in meditations. One of our members here paints them and recieves messages from them in meditations.
Regarding my experience- I did not see this Being, but I heard her sing as well to me. She sang just as you described– but not in a foreign language in my case, because she had a message for me .
Earlier that month that I heard her, I had a wonderful faery encounter which made me really want to make an effort to help Nature out any way I could- and help the faeries out. One morning before my alarm clock went off for me to get ready for work, — around 6:00 am, I heard this woman singing this verse to me– in a high pitched adult's voice:
"You are helping the flower to seed; all things are precious"
was what she sang to me. I was half asleep/half awake when she sang this, and her song made me wake right up and record what I had heard immediately in my journal. Her song has inspired me to this day to really open my heart and do whatever is in my power to minister to the animals and plants around me– to do what I can to help the Faery . As I write this, I am feeling alot of enthusiasm to pick up some garbage I saw on a road not far from where I live. That is one way to help the Faery– who see the things we humans do to this Earth– Little things we can do like Picking up trash puts a smile on thier faces, because finally a human is actually working WITH them instead of making thier work harder!
So, yes, there are definitely these Sidhe Beings– in fact, the painting of the woman's face on the top of our website reminds me of one of these Beings- I believe she could be an Elven woman though- Whatever the case, I feel that who you saw was not a human– but I sense that she is definitely someone who works on the side of Light.