One way would be to order by the count in descending order, and then just take the topmost row:
SELECT timeArrive
FROM tablename
GROUP BY timeArrive
ORDER BY COUNT(timeArrive) DESC LIMIT 1;
However, if there is more than one value that has the maximum count, the others will be ignored. A possible solution to that might be to use a subquery, e.g.,
SELECT timeArrive
FROM tablename
GROUP BY timeArrive
HAVING COUNT(timeArrive) >= ALL (SELECT COUNT(timeArrive) FROM tablename);