1height; level; (music) pitch
2relative superiority
3propriety; discretion (usu. in the negative, e.g. 不知高低)
4no matter what; just; simply (will not ..., must ... etc)
5at long last
Examples
dì miàn地面gāo dī高低bù píng不平，gěi给bù duì部队qián jìn前进dài lái带来le了kùn nan困难。
地面高低不平，给部队前进带来了困难。
The rugged terrain made the troops' advance difficult.
生活中有高低起伏。
In life there are ups and downs.
人生充满了高低起伏。
Life is full of ups and downs.