"The woman eats salt."
Translation:Kadın tuz yer.
Subjects are never in the accusative case. Never ever ever.
The accusative case is for specific direct objects and for some time expressions :)
If it would be "tuzu", you would need to translate as "the woman eats the salt".
The former is in the nominative case and is used for subjects and general direct objects (meaning you would just say "salt" as a direct object). Tuzu is in the accusative case and is for specific direct objects (meaning you would have to say "the salt" as a direct object). Tuzu will never show up as a subject if it is in the accusative case.
p.s. tuzu could have a different suffix on it as well that you will learn later :)
It is a statement, we try to say "Deniz tuzlu olur" here, so we use the suffix "-dur".