How to improve positional chess understanding? I am a normal player with ~1500 FIDE rating, and I am quite good at tactics and trap things. But I falter at the positional games and I am bound to make mistakes where the things are non-tactical. So how should I improve my positional chess understanding?
My suggestion ist to take a book on positional chess and look through it.  For example "How to Reassess Your Chess" by IM Silman is, in my opinion, a good book to get started.  It walks you through all of the positional elements and gives you at least a good idea on what you might want to look out for.  Of course this can only be a start and at some point you may have to look beyond for some ideas on pawn structures, for which also several good works are available.

One word of warning is that, often, while you may feel that the weakest part of your game is positional chess, this might not be correct.  You can be sure only if a show a couple of your games (especially losses or games where you ended up in an uncomfortable position) to a (quite a bit) stronger player and ask their opinion.  

In any case, I would like to recommend also the book series by Yusupov, in particular for your level the Fundamentals series (orange color).  These books contain positional chapters, but also endgame, tactics, openings and much more.  The goal is to raise the level of all your abilities to the same level.  If you can breeze through the tactical parts, this is good for you, then you will mostly gain from the positional chapters. However, it is likely that you will find further parts where you can learn a lot.