Measuring an algorithm's efficiency

I need help filling this out. I tried to fill out the first portion got I got confused. I'd appreciate if you explain some of them for me to get a better understanding.

Measuring an algorithm's efficiency A good algorithm is correct, but a great algorithm is both correct and efficient. The most efficient algorithm is one that takes the least amount of execution time and memory usage possible while still yielding a correct answer. Counting the operations One way to measure the efficiency of an algorithm is to count how many operations it needs in order to find the answer across different input sizes. Let's start by measuring the linear search algorithm, which finds a value in a list. The algorithm looks through each item in the list, checking each one to see if it equals the target value. If it finds the value, it immediately returns the index. If it never finds the value after checking every list item, it returns -1. You could also take a look at the following code: public static int search (int[] numbers, int targetNumber) { for (int index = 0; index