In Rust programming, a "for loop" is a type of loop that allows you to iterate over a collection of items, such as an array or a vector. The basic syntax of a for loop in Rust is as follows:

for variable in collection {
    // code to execute for each item in the collection
}

For example, you can use a for loop to iterate over an array of integers and print out each value:

let numbers = [1, 2, 3, 4, 5];
for num in numbers.iter() {
    println!("{}", num);
}

In this example, the for loop iterates over the numbers array, assigns each value to the variable num, and prints the value of num at each iteration.