This is a very technical question :). I will use USD for the example. There are 100 pennies in a dollar. A revaluation would be there are now 50 pennies in a dollar or 150 pennies in a dollar. This changes the value of a penny.
Devaluation means my dollar is worth less now than it used to compared to other currencies. I used to get 1.5 euros for my dollar. Now I only get one.
Appreciation and depreciation are how an asset's value changes over time. Today, people will pay 100 dollars for my watch. If it appreciates, they will be willing to pay more in the future for it. If it depreciates, it is worth less in the future. People invest in things hoping they will appreciate.