僕、無芸大食で何の取り柄もないんです。

、。

I've got no talent and a huge appetite — nothing really going for me.

Literal

I [topic-、], no-talent-big-eater [being-で] what [of-の] merit [also-も] not-exist [explanatory-んです].

無芸大食 is a 四字熟語 (four-character compound) literally '[no] art [big] eating' = 'having no talents except eating.' A self-deprecating set phrase. 取り柄 ('redeeming feature, good point') takes も for emphasis + negative. A humble but somewhat exaggerated self-introduction.