The Lewis structure of P₄ is shown in 3-D form. The two bottom corner P atoms are facing right in front of us, one P atom behind the two, and one P above it. Each line represents 2 electrons. When you add the lone electrons, you get a total of 20 valence electrons.
Formal charge of each P: 5 - (2 +1/2*6) = 0
Formal charge of each P: 5 - (2 +1/2*6) = 0