understanding tkprof sql*net message

hello gurus,

     i use tkprof because i had got times response very low and when i see the file's tkprof, i see only.

       SQL*Net message from client                   677      338.96        641.66

     1 - i would like know what is it ?

     2 - is the time in second ?  677      338.96        641.66

best regards

JP

>>>>>>>>>>>>>>>>>>>>>

Elapsed times include waiting on following events:
  Event waited on                             Times   Max. Wait  Total Waited
  ----------------------------------------   Waited  ----------  ------------
  SQL*Net message to client                     677        0.00          0.00
  SQL*Net message from client                   677      338.96        641.66
  db file sequential read                         2        0.00          0.00
  log file sync                                  13        0.00          0.01
  SQL*Net more data from client                   8        0.00          0.00
  SQL*Net more data to client                    69        0.00          0.00

OVERALL TOTALS FOR ALL RECURSIVE STATEMENTS

call     count       cpu    elapsed       disk      query    current        rows