In Polish, we very often use phrases such as: On już nie żyje. This is a phrase we don't recommend translating word-for-word into English. The phrase "He already doesn't live" is very unlikely to be understood. The closest acceptable phrase would be: "He's no longer among the living."
In most situations, we use the regular verb to die. (die/died/died)
For some reason, many Polish speakers tend to use constructions like: He die / The man die. This is incorrect for several reasons. First of all, if we're in present simple, we need to add an s for he, she, the man, etc.: He dies / The man dies. But remember: present simple is used for what generally/usually/often happens, and most of us only die once. So we don't use this verb very often in present simple, except when we are being philosophical
A coward dies a thousand times; a brave man dies only once.
or when we are making general statements, in which case we usually use a plural subject
People very often die around the holidays.
or when we are using the verb in a metaphorical sense, meaning to suffer greatly, as in this song by the Magnetic Fields:
I die when you walk by.
Most often, we use the verb to die in past simple. Often we'll give a date or time, or a sequence of events:
My uncle died just before Christmas in 1976.
Piłsudski died in 1935.
She gave each of her children her blessing, and then she died.
In the case of someone who dies in a war, a disaster, an accident, etc., we can also use the passive form of kill:
They were killed in a terrible plane crash.
Theoretically, we can use to die in present perfect, but it's unusual, at least in the U.S., except perhaps in news bulletins:
The mayor of Nowhereville has died in a car accident.
It's more often used in past perfect, as the "past of the past":
He cried when he found out his old girlfriend had died the year before.
Rather than a literal translation of On już nie żyje, we are more likely to use to be + adjective. The adjective in this case is dead. The opposite is alive.
He's dead. In fact, he's been dead for years.
She's not dead at all. She's alive--I just saw her five minutes ago.
For some people, the words die and dead are too harsh. They prefer euphemisms:
He's gone. In fact, he passed away years ago.
We can use the adjective late in front of a person's name to show that he or she is dead:
The late John F. Kennedy was the 35th president of the United States.
Many people are still mourning the late Princess Di.
but we cannot say
because in this structure it means that a person simply isn't on time (for a meeting, school, etc.)
Note that death can be seen as a process, so the verb is often used in progressive, or continuous, form:
The patient is dying.
Here, too, the verb is often used in a metaphoric or exaggerated sense:
Can you open a window? I'm dying of suffocation in here.
This sense is used quite often in the famous film Dog Day Afternoon with Al Pacino.
Then, of course, there are the various future tenses:
If we don't do something soon, this man will die.
She's going to die and there's nothing we can do about it.
The prisoner dies tomorrow in the electric chair unless he is pardoned. (This is an event that's actually been scheduled.)
Since death is usually a sensitive subject, it's a good idea, if you use English, to be prepared to talk or write about it, in order to avoid possible embarrassment. We hope these tips will be helpful.