I know that 'rale' means 'to pull', but what doe it mean here: "li fè yon bon jan RALE sou sijè sekirite lekòl la"

fè yon bon jan rale → to discuss in depth, to go into great details, to go a great distance
1.
"Li te fè yon bon jan RALE sou sijè sekirite lekòl la"
"He/She spoke extensively on the subject of school security"

yon bon rale also means a good distance, a little far

2. 
   Magazen an yon bon rale sot isit la. Ou pa ta dwe ale apye. Ale sou bekàn pito.

   The store is a good distance from here.  You shouldn't walk. Take your bike instead.

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