Okay kiddo, have you ever heard someone say "arigatou" instead of "arigatou gozaimasu" in Japanese? That's an example of an abbreviated word! Abbreviated words are shorter versions of longer words or phrases. They're kind of like nicknames for words.
Japanese people use a lot of abbreviated words because it's easier to say them quickly and they make conversations go faster. They also use them in casual situations like talking with friends or family.
Another type of word that Japanese people use a lot are called contracted words. These are words where two or more words are put together to make a new word. For example, "Kombini" is a contracted word for "konbiniensu sutoa" which means convenience store.
Contracted words are also used a lot in Japanese because they make conversations go faster too. They're kind of like puzzle pieces that fit together to make a bigger word, just like how legos fit together to make a tower.
So, when you hear someone speaking Japanese and using words like "arigatou" or "kombini", you'll know that they're using abbreviated and contracted words to talk more efficiently!