深入浅出

shēn rù qiǎn chū

to explain a complicated subject matter in simple terms (idiom)

(of language) simple and easy to understand

深

shēn

deep (lit. and fig.)

入

rù

to enter; to go into

浅

qiǎn

shallow

出

chū

variant of 出[chu1] (classifier for plays or chapters of classical novels)