Typically it would depend on the browser where the "bookmarks" existed and the browser where you want to place the "bookmarks".
Since you are referring to the task as "bookmarks" rather than "favorites" I will assume either Chrome or Firefox rather than I.E. or Edge.
Your best bet would be to use the native bookmark manager in either browser to export the bookmarks as an html file since both browser keep their bookmarks in a proprietary format but both offer the option to export to and then import from an html file.
If they were just plain old I.E. favorites you could just drop them in C:\Users\YourUserName\Favorites, and then.....
Import them into Firefox and Chrome