How does "qpois(1-pvars, 3, .25) " work in R ?

#1
R code :

Code:
library(MASS)

mu <- rep(0,4)
Sigma <- matrix(.7, nrow=4, ncol=4) + diag(4)*.3
rawvars <- mvrnorm(n=10000, mu=mu, Sigma=Sigma)
 pvars <- pnorm(rawvars)

binomvars <- qpois(1-pvars, 3, .25)
I have not understood how does qpois(1-pvars, 3, .25) work ? What is the interpretation of qpois(1-pvars, 3, .25) ? In R documentation , qpois(p,lambda) .

Then what is 3 and .25 inside qpois() ?

If I ran the code qpois(1-pvars, 3, .25) , I get value from 0 to 12 . Why ?

How qpois(1-pvars, 3, .25) generates binomial variables ?