The life instinct or Eros was one of the two basic instincts described by Freud in Beyond the Pleasure Principle (1920g), when he began to construct his structural theory, in which the life instinct stands opposed to the death instinct. The life instinct subsumed uninhibited sexual instincts, instinctual impulses inhibited in respect of their aim and sublimated, and the instincts of self-preservation.
Life instinct = in psychoanalytic theory, the instinct of self-preservation and sexual procreation.
In the U.S. we say, "Go with your gut." or "What's your gut telling you?" Sometimes we say, "Go with your gut instinct." It's intuition. It's the ability to form a judgment without using the reasoning process. If I ask you "What's your basic instinct?" I'm asking you to tell me your first impression, feeling, or the action you would like to take. If my child is bleeding, my basic instinct is to call 911. My gut tells me it's the right thing to do. Hope this helps more than it confuses.