The causes of row contentions

Hi all,

for security reason I have removed the SQL on which referring tables name.

it is the part of addm report

my concern what is the reason behind row contentions.

       RECOMMENDATION 1: Application Analysis, 2% benefit (7608 seconds)
      ACTION: Significant row contention was detected in the INDEX
         "xxxx.xxxxxx" with object id 566394. Trace
         the cause of row contention in the application logic using the given
         blocked SQL.
         RELEVANT OBJECT: database object with id 566394
      RATIONALE: The SQL statement with SQL_ID "4drqk5m36ffn2" was blocked on
         row locks.
         RELEVANT OBJECT: SQL statement with SQL_ID 4drqk5m36ffn2
         UPDATE "xxxxxxxxx" "A1" SET "STATUS_V" =