A cemetery is a place where dead people are buried. People mark the place a member of their family is buried with a gravestone.
A coffin is a box that a dead person is put into. Coffins are either buried in a cemetery, put inside a mausoleum or burnt into ashes in a crematorium.
Something is dead if it used to be alive once but isn't any more. All living things will eventually die, but some can live for much longer than others.
Dying is the point where something alive becomes dead. The term can also be used on things that aren't alive, to describe when things like engines and other appliances stop working.
A funeral is a ceremony that happens soon after someone dies. Funeral ceremonies vary between different countries and customs.
In stories, a ghost is the spirit of a person who has died. You might dress up like a scary ghost for Halloween.
A grave is somewhere you bury someone when they die. Graves and graveyards, or cemeteries, are usually only set up for people. Pets are usually buried in your backyard when they die. Graves are usually marked with gravestones with the name of the person and when they were born and when they died written on the stone.
A gravestone is a marker, usually made of stone, that shows where a grave is and gives some details about who is buried there.