In this SE you will prove your writing skills in a range of text types meant for publication: reports, articles, reviews and essays. Your language competence needs to be at B1 level, which means that...
... you can write text that is clear and well-organised.
... you can describe your feelings, experiences and opinions on things you have done or seen.
... you can describe the advantages and disadvantages of issues you have an interest in.
... you can summarise facts and outline a report about it.
... you have enough vocabulary to convey the main idea about various topics with reasonable precision.
... your grammar is reasonably controlled and generally good. Errors may occur, but do not hinder meaning.
... your spelling, punctuation and layout are accurate enough to be followed most of the time.