N5
ている②
State of being, Has (have) done
お母さんは今買い物に行っています。
My mom is out shopping right now.
Explanation
「〜ている」 has a second meaning: an action that happens in an instant is finished, and its result remains up to now. Examples: 「結婚する」 (marry), 「死ぬ」 (die), 「壊れる」 (break), 「太る」 (get fat), 「座る」 (sit down), 「着る」 (put on). With 「ている」 these do not mean 'is doing' but 'is in that state': 「結婚している」 means 'is married', not 'is holding the wedding right now'.
Mixed up with
The negative of 「知る」 is an exam favourite: 「知っています」 means 'I know'; the negative is not 「知っていません」 but 「知りません」 (the moment of getting to know has not happened).
Keep action in progress and resulting state apart: 「服を着ている」 means you are wearing clothes; for the action of putting them on you can say 「服を着ているところだ」. 「電車に乗っている」 means you are on the train, not stepping on right now.