Today, "he (or she) is peace and love" is a term used to describe the behavior of a relaxed person, whose look recalls the New Age movement and hippie or being a pacifist.
The term was particularly used in the 1960s to refer to working peacefully protest against the Vietnam War.
The symbol associated ☮, was invented by the British graphic designer Gerald Holtom during a demonstration in 1958 against a nuclear weapons factory. In this symbol can be seen in language semaphore (used in the British navy) an N and a D which stands for Nuclear Disarmament (Nuclear Disarmament).
For some, the sign inside the circle is also a rune of the Futhark alphabet .
Only later, in the 1970s that the symbol was taken up by the hippie movement for the reasons mentioned above.