笨 can mean intellectually dull or physically clumsy: 笨手笨脚 (bèn shǒu bèn jiǎo, clumsy hands and feet). It's often used self-deprecatingly: 我太笨了 (I'm so dumb).
memory
The character has 竹 (bamboo) on top and 本 (root/origin) below. Think of bamboo — it looks simple and basic on the inside. Sometimes associated with a 'wooden' or slow quality.
