Final answer:
The nickname for mainland France is 'l'Hexagone' due to its hexagonal shape. There are currently 18 administrative regions in mainland France, each divided into departments and communes/municipalities.
Step-by-step explanation:
The nickname for mainland France is 'l'Hexagone' because of its roughly hexagonal shape. France is commonly referred to as l'Hexagone due to its six-sided shape on the map.
There are currently 18 administrative regions in mainland France, which were reorganized from 13 regions in 2016. Each region is further divided into departments, and each department is made up of communes or municipalities. These administrative divisions help facilitate local governance and provide services to the population.