Başak Klasik Mısır Unu is corn flour (maize flour) in a 400 g bag. The front shows yellow corn on the cob and repeats the name in several languages, including English ('Corn Flour'), German ('Maismehl') and French ('Farine de Maïs'), so it is easy to spot on the shelf.
In Turkish kitchens mısır unu is closely tied to Black Sea cooking: it is the base of cornbread (mısır ekmeği), it goes into cheesy, buttery dishes such as kuymak and muhlama, and it is the classic coating for pan-fried anchovies (hamsi tava). At home it can also be combined with wheat flour in breads, pancakes and cakes for a more golden colour and a slightly coarser crumb. Corn flour absorbs liquid differently from wheat flour, so follow the proportions given in your recipe.
This is ground corn flour, not the white corn starch (mısır nişastası) used to thicken puddings. Close the bag tightly after opening and store it in a cool, dry place. Check the allergen information printed on the pack if you are cooking for someone who must avoid gluten.