R function explain cat function?

Use the R script to finish the following operations ( Explain question 3)

(1) Use ’rexp’ to generate 50 exponential random variables with rate 2, and store them in a vector called ’rand.vec’

(2) Turn the vector ’rand.vec’ into a 5x10 matrix with option ’byrow = T’, and assign the name ’rand.mat’ to the matrix.

(3) Use ’cat’ function to output the value of the elements in the 4th row of the matrix whose value is greater than 0.5.

My code:

rand.vec <- rexp(50, rate = 2)

rand.mat <- matrix(rand.vec, nrow = 5, byrow = T)

cat(rand.mat[4,rand.mat[4,]>0.5])

Can you explain the cat function and how the code "cat(rand.mat[4,rand.mat[4,]>0.5])" extracts elements in the 4th row of the matrix whose value is greater than 0.5.

thank you