Ta książka jest czerwona.

Ta książka jest czerwona.

Ta książka jest czerwona. This book is red. Notice she didn't just say to this time, she said ta. Because in Polish, objects have genders. Książka ends in an a, making it feminine.

So 'this' becomes ta, and the adjective for red — czerwona — also takes that feminine a ending. The c-z sounds like a hard ch, and the w is a v. Czerwona.