English Translation
Since he doesn’t know anything about it, his opinion is worthless.
s’y connaître [être expert] :
s’y connaître en architecture = to know a lot about architecture
je m’y connais peu en informatique = I don’t know much about computers
ah ça, pour râler, il s’y connaît ! familier = he’s very good at grumbling!
pour les gaffes, tu t’y connais ! familier = when it comes to blunders, you take some beating!
c’est un escroc, ou je ne m’y connais pas ! = I know a crook when I see one!
© Larousse 2014
s’y connaître gets used several different ways, so I put in all the Larousse sentences.