This is a cross depicting the figure of Christ crucified on it (as distinct from a bare cross) and is widely regarded as a symbol of Roman Catholicism. Meanwhile Protestants consider the image focuses too heavily on Christ's death and not on His resurrection.  Crucifixes can vary in size from those worn around the neck to life-size replicas.  While wearing a cross or crucifix does not make a person a Christian, as it can be a fashion statement it can be a witness to being a Christ follower.  

See also: cross.