It's not 6.2% in the last month, although the article doesn't do a good job of explaining what the reference point is. The percentage refers to how much higher the CPI is than the same month the previous year.

So it mentions that February's value was 5.5%, predicting to go to 5.9% in March, with March's actual value being a bit higher than the prediction at 6.2%.

That means the CPI in Feb 2022 is 5.5% higher than the CPI in February 2021, and similarly was 6.2% higher this month than in March last year.

The actual numbers themselves are pretty fuzzy, as the "basket" of goods that are assessed as part of the CPI can vary from year to year, and varies from country to country. Plenty of areas can see much different changes than what these numbers list. But it's at least a useful gauge to see what direction it's moving in, and how extreme it is.