(=passablement) quite, fairly
Il est assez fort. He's quite strong., He's fairly strong.
C'est assez bon. It's quite good., It's fairly good.
Il est passé assez vite. He went past quite quickly., He went past fairly quickly.
Il faisait assez beau. The weather was quite nice., The weather was fairly nice.
Ça me plaît assez. I quite like it.