First of all, how should we define the centrality? Literally, it just indicates the node is "central" to the network, which could indicate some sort of importance, significance, or having a nadvantaged position. However, that there are lots of specific ways we can think of centrality, and thus different ways of mathematically defining the concept.
Degree centrality measures how connected is a node. Thus, the degree of a node is a simple measure of centrality in which more highly connected nodes rank higher.