Let us keep it as understandable as possible. Inflation is the increase in value of your money in the future while deflation is the decrease in value of your money in the future. That is it. Say for example in inflation, if you have $1 now, you can buy 10 sodas. But immediately two years after, if you have $1, you can only buy 5 sodas with it. In deflation, if you have $1 now, you can buy 10 sodas. But immediately two years after, if you have $1, you can buy 20 sodas with it. Simply put, the value of your money today and in the coming years depends on how well the economy worldwide is doing.
In the world of trading there are a lot of code words just like inflammation and deflation are also used. Inflammation in trading means that the rate of your money is increased in the future for example you have 1usd dollar and you can buy 5 pencil now and after some time you can bought 7 pencil then it is called inflammation while deflation mean decrease the value of money in future.