Verified answer

It means, "What pleases the prince has the strength of law." Princeps here referrred originally to the Roman emperor. But in the countries which used Roman law in later times this tag could be quoted to prove what the law was in some circumstances. It meant that something became law just because the ruler wished it to be.

Some of the words can be rendered in different ways but the basic idea is clear. Here are some ways of translating the motto.

What was acceptable to the leader has the force of law.

That which was pleasing to the ruler holds the force of law.

You might translate freely as "whatever keeps the boss happy has the strength of the law."

Habet Latin

and beginning appeased law government vigor