The story this coin tells is of reconstruction after the second world war.
The king of Belgium did not leave the country. The queen of the Netherlands left and became a symbol of resistance. The king of Denmark stayed and behaved in such a way that he became a symbol of resistance. The king of Belgium's behaviour was open to criticism. Even when he was succeeded by Boudewijn/Baudoin, there were widespread misgivings against the royal house. This is the reason the early coins of king Baudoin/Boudewijn do not have a portrait of the king.
The other side of the story is the climbing lion holding the constitution. It is an image from the first series of coins after Belgian independence. It refers here to the resurrection of Belgium as an independent state after the nazi occupation.
Historically, Belgium, the birthplace of Charlemagne, was a military football for the later Frankish kings of the West (France) and the Frankish emperors of the centre (Germany). Some areas developed into French speaking, others into Flemish (a form of Dutch) speaking and they didn't get along for centuries. The language division developed into an economic division when minerals were found and mined in the French areas. It became a religious and political division as socialists, supported by a majority of the Flemish speakers, took over education and caring for the poor, while conservatives, supported by a majority of the French speakers wanted the church to continue doing that. When the mines became un-economical, the Flemish part acquired more rights, very slowly. This is why this coin exists with Dutch texts also.
After the second world war, there was widespread destruction in Belgium. In particular, the port of Antwerp and the airports had suffered heavily and the railway system was wrecked. However, Belgium still had a well-trained workforce. With the invaluable help of Marshall aid that provided starting capital, economic reconstruction could begin. The situation was the same in neighbouring countries, notably Germany, a large Belgian export market. That gave the whole process a boost. The silver in this coin symbolises the success of reconstruction.
Peter