Sometimes life just feels too difficult that for some people the only option they believe is to take their own lives.
Talking to the right person can sometimes offer the individual a safe and supportive place for them to work through what their hopelessness may be about.
The counselling directory has some great advice : http://www.counselling-directory.org.uk/help-someone-who-is-suicidal.html
This offers a range of ideas how to talk to a suicidal friend and some of the Myths around suicide.
If someone you know is struggling encourage them to seek help , GP , AMHS, Samaritans, A local Counsellor or Psychotherapist.