A tughra is a special kind of symbol, kind of like a stamp or signature, that was used by Ottoman sultans (or, like, kings) a long time ago. It's made up of a bunch of fancy letters and shapes, all lined up together in a special way.
Think of it like this: have you ever seen your name written in cursive, where all the letters flow together in a pretty way? That's kind of what the tughra looks like, except instead of just letters, it's made up of special symbols and shapes.
The Ottoman sultans would put their tughra on important documents and official letters, kind of like how you might sign your name at the end of a card or letter. It was a way to show that they approved of or agreed with whatever was written in the document.
Nowadays, we don't really use tughra anymore, because the Ottoman Empire doesn't exist anymore and we have different symbols and ways of signing things. But it's still an interesting part of history!