The number of those who traveled by plane during the Bon holiday is the second smallest ever.
"利用者は過去2番目に低かった"
飛行機を利用した人々 those who traveled by plane
お盆期間中 during the Bon holiday
～の数 the number of ~
過去２番目に the second smallest ever
The number of those who traveled by plane during the Bon holiday is the second smallest ever.
日本 
