Thank you, everyone, now I understand, so the summary merit is airdrop from forum to users.
is this airdrop every year or its just one time ?
Merit summary is the merit record of a profile which includes 120 days records of send and received merits.If you see no record at merit history then the user didn't received any merit in last 120 days.
If you want to see full merit history of someone you can use Loycev's tool or just visit
https://bpip.org/default.aspx and search for the profile to get full merit history.