"The strawberry is tasty, thank you!"
Translation:התות טעים, תודה!
Because there is no direct object in this sentence. את marks definite direct objects.
את is also a definite article marker, meaning that the direct object marked in the sentence is always definite whether it has a ה or not but more often than not, the object will have a ה
I thought every word ending with ת or ה is considered female. The rest male?
That is usually true, but there are exceptions that we have to learn one by one. Thankfully, we will be still be understood if we make mistakes. More info available here: