There are apps/online sites for currency conversion as well as loan calculators.
Just type in "currency converter" or "loan calculator" into your search engine. Multiple sites available.
I know this is different than "understanding" the topic, but at least you're likely to get the information you need.
To not have a full grasp of these concepts, especially when it comes to credit cards and loans, is not uncommon. Of course, these banking institutions also throw in "finance fees" and a handful of other fees that can make a "low interest" loan every bit as expensive as a "high interest" loan without the fees. You really have to dig into the details to sort out if you're going to get "screwed" on a loan or not. Debt is a huge issue for many.
Now, throw in things like investment portfolios with all the different types of retirement accounts, money market accounts, ETFs, stocks, bonds, "high risk/high reward", "low risk/low reward", and so on, it can be quite intimidating and confusing.
I don't want to hijack this thread from its primary focus, but a lot of people struggle with their knowledge on these topics. It's a million and one things they never taught us in school. You sort of have to make this a "special interest" and really dig into it. I am convinced that it is one of the primary reasons why the rich become richer and poor become poorer. A kid growing up with a silver spoon in his mouth, with wealthy a family, even if at 18yrs old, they cut him/her off totally from the money, WILL most likely be wealthy within a few years even if they start from nothing. Why? Knowledge. The wealthy have a totally different relationship with their money. They borrow money to make more money. They don't buy "things". They invest. They will go hungry, have nothing, and are willing to suffer in the beginning at seemingly "high risk" in order to achieve a payout in the end. They know how the "rules of money" can be played to their advantage because they sat around the dinner table for their entire lives discussing these things. They know who to talk to. They know the art of "the deal". They know you don't make money, that is, not significant amounts of money when you are an employee. You have to be the owner, the CEO. The majority of us schmucks have been told "If you work hard, live within your means, and save your money, you can get ahead in life." That's not true in the least. Myself and my children were taught in school, our parents, our friends, just enough to become good employees, but not how to make money so that we didn't have to work at all. Why would I put money into a savings account that makes 1-2% interest per year when I can make smart investments and make over 100% per year? I didn't realize this was possible until I started investing on my own. I've 6X my investments in just 3 years! This is just me "dipping my toes" into the market. People who fully commit will borrow 10's of thousands of dollars (buying on margin) at 10% interest, in order to invest in something that might make them 20, 40, 80, 100% interest. Pay off the loan, take out another loan for 100's of thousands of dollars and do the same the next year. This concept and thought process and risk taking is not for the faint of heart, which probably most poor people would never consider. The things never taught to us, that now that I am in my 50's and staring at retirement, I am just discovering this world. Had I known this when I was in my 20's, I'd be living a totally different life.