"用通俗语" can be translated into English as "use plain language" or "speak in simple terms".
"Use plain language" emphasizes the use of straightforward, uncomplicated vocabulary and expressions.
"Speak in simple terms" conveys the idea of communicating in a way that is easy to understand, avoiding overly technical or complex language.
Both expressions effectively convey the meaning of using language that is accessible and easily comprehensible to a general audience.