Almost all Russian verbs have two aspects: the Imperfective and the Perfective. There are many rules to be able to use them properly, bus the basics are:
The Imperfective aspect:
is used when we speak about an action as a process:
Я читала книгу. I was reading a book.
is used when we speak about a regular action:
Я буду читать книги каждый день. I will read books every day.
The Imperfective aspect has three tenses: Present, Past and Future.
The Perfective aspect:
is used when we speak about the result of an action:
Я прочитал книгу. I have read the book.
is used when we speak an action that happens once:
Я прочитаю книгу завтра. I will read the book tomorrow.
The Perfective aspect has two tenses: Past and Future.
In the case of "Pass the salt, please" it is the Perfective aspect, because a one-time, precise action is meant here, so the translation will be: "Передай мне соль, пожалуйста".
Russian Language Teacher.