The phrase "kent his" is a Scottish slang term meaning "knows his." There are several synonyms for this phrase that could be used interchangeably depending on context and dialect. Some options include "knows his stuff," "has expertise," "is knowledgeable," "is familiar with," "has a good handle on," and "is well-versed in." Each of these phrases conveys a similar idea of someone who is well-informed and capable in a particular area or subject matter. By using these synonyms, you can add variety and nuance to your language while still communicating the same essential message.