The staff were so courteous and efficient, and the atmosphere was intimate and relaxing.

efficient 是形容词，由前缀 ef-（表示"向外"）和词根 fic（做）加上后缀 -ient（表示"具有...性质的"）组成，字面意思是"能够把事情做出来的"，引申为"高效的、有效率的"。