J
何言ってるんだ…?
このくらい研修医一人でやるのはどの病院でも常識だぞ
Vocabulary
何 what
言ってる slurred 言っている to be saying
んだ slurred のだ adds emphasis
このくらい that much
研修医 doctor in training + 一人 one person → one single doctor in training
で particle indicating mean/method
やる to do (informal)
の nominalization
は topic
どの … でも which(ever) …/ in any …
病院 hospital
常識 common sense
だ copula
ぞ emphasis (not super nice)
Interpretation
What (the heck) are you talking about?
Having a single doctor in training doing that much is common sense in any hospital.