你弟弟会画画英文可以说："Your younger brother is skilled at drawing."

来源：
这句话的来源是你弟弟会画画这一事实。"Your younger brother" 指的是你的弟弟，"is skilled at" 是一个表示能力的短语，意思是"擅长于"，"drawing" 是一个名词，意思是"画画"。

一些英文例句和中文翻译：

"Your younger brother has a talent for drawing." 你弟弟有绘画天赋。
"I admire your younger brother's abipty to draw so reapstically." 我很佩服你弟弟画得如此逼真的能力。
"Your younger brother's drawings always impress me with their detail and creativity." 你弟弟的画总是令我惊讶的细节和创造力。