tsh is your thyroid stimulating hormone. Low is generally OK. when it's high then your body is working too hard to produce thyroid hormone and you need a thyroid supplement/med such as synthroid. Did they mention anything else?
Actually low isn't great either as its an indication you have an overactive thyroid. I've had one for a few years and have to take a thyroid suppresant. My TSH levels have slowly increased and now I have been able to stop the meds.
I was told though that there are meds you can take when you are pregnant and/or breastfeeding.