Well, Mr Jessy, for an English speaker, it is certainly not easy, but it is not any harder than the Turkish. If you know Arabic, I imagine it would be a breeze. Actually, it has a lot fewer beta problems than some of the other languages have had, and like the people on the Turkish discussion board, those on the Hebrew board are very helpful.
No, confusing as it seems, "twin bed" is simply a size of bed, like double and queen. Actually, I see now that many online dictionaries to have the meaning you are talking about here, so that may be the typical usage in the UK or Australia. The use of the term in North America is generally what I see here: https://www.homedit.com/difference-between-the-varied-bed-sizes-king-queen-twin-single-full/