Alright kiddo, so you know how some people speak different languages, right? And sometimes, people need to write down those languages using different letters, called alphabets.
Well, in Belarus, they speak a language called Belarusian. And, depending on who you talk to, they might write it down using different alphabets.
One of those alphabets is called Cyrillic, which is also used for Russian. But sometimes people might use a different alphabet called Latin, which is the same one we use to write English.
Romanization is the process of taking those Cyrillic or Latin letters and turning them into the letters we use in the English alphabet. It helps people who don't speak Belarusian understand what the words mean without having to learn a whole new alphabet.
So basically, romanization of Belarusian is just a way of writing it down using the same letters we use for English, so more people can read and understand it.