I am currently working on logistic regression in R and I have trained the model but when I am looking at features of model, I am not able to understand what is Null and Residual deviance explains ?

data(mtcars)

names(mtcars)

model1<-glm(formula=vs~wt+disp,data=mtcars,family=“binomial”)

model1

Call: glm(formula = vs ~ wt + disp, family = “binomial”, data = mtcars)

Coefficients:

(Intercept) wt disp

1.60859 1.62635 -0.03443

Degrees of Freedom: 31 Total (i.e. Null); 29 Residual

Null Deviance: 43.86

Residual Deviance: 21.4 AIC: 27.4