In this statement, Maslow is arguing that not all of our needs are equally important. Some needs, such as food or thirst, are our priority, and only when we satisfy these do we begin to think about others such as love and self-esteem.
An example that shows this are people who live in extreme poverty and steal food. People in this situation would rather compromise their safety, freedom and maybe even self-worth in order to satisfy their hunger.
However, some evidence points to the opposite as well. For example, soldiers who join the war do so to fulfill abstract needs such as earning respect and finding meaning, even if this means risking their safety, having little to eat and facing many uncomfortable situations. Another example is athletes. Athletes train to a degree that is uncomfortable and hard. They also limit their food intake to certain types of food in order to achieve goals such as self-fulfillment and a higher self-esteem.