We have worked through all of the lessons in order and today is the 10th lesson
Today we have reached the 10th lesson in the course
「一番から順序どおり始めて今が１０番目です」＝ We have worked through all of the lessons in order and today is the 10th lesson / Today we have reached the 10th lesson in the course
ボキャブラリー
work through ＝ 順番に飛ばさずに全ての授業をやる
in order ＝ 順番に、順序どおり
10th lesson ＝ 10番目のレッスン
reach ＝ たどり着く
イギリス 
