For context: my language partner wrote me back and she explained to me in Japanese the use and grammar behind "て-form + いる" in the context of one's personal past.
The sentence in question (including some pretext):
「 大学の勉強の間、移住者の子供にドイツ語を教えるアルバイトをしています」 について考えてみましょう。
アンドレアスさんが言っているのは、「経験・経歴を表すテイル形」のことだと思います。
My attempt at translation of the bold part:
"Concerning what Andreas said, I think it is 'experience/personal history revealing TAIL-FIGURE'".
This "Tail-figure" doesn't make much sense, at least to me since I have no idea what it is supposed to tell me...^^
I would be happy if someone could elaborate :=)