@nonono91 For the most part the books stand alone. Some pointers is to look at the covers of the book. If It has a number on the cover it lets you know at least what number the book is in whatever series it belongs to. If not that then the title itself may be an indicator by informing you. The next tip is to read the description, sometimes I mention what number the book is and in what series it is in there. Lastly, read the info pages. If ever you can't tell from the clues above, the info page will always let you know where the book stands if it is in a series/duo/trio/saga (etc.).
On top of all this, some stories do mention characters from other stories, but it's not mandatory that you read that other story to understand it's just something I like to do. Hope that helps, if not let me know.