1to break new ground (for agriculture)
2to open up (a new seam)
3to develop (border regions)
4fig. to open up (new horizons)
Example
nián qīng年轻de的shí hou时候nǐ你yīng gāi应该kāi tuò开拓nǐ你de的sī xiǎng思想。
年轻的时候你应该开拓你的思想。
You should enrich your mind when young.