In English some nouns have a plural form. (複数) We use this form if there are more than 1 of something.
1 person 2 people
1 child 7 children
Most nouns that we can count only need an S at the end of the word to make it's plural form.
1 basket 4 baskets
1 flower 100 flowers
Here are 3 English words written in katakana that are common in Japan.
Because the kana ツ makes a tsu sound at the end of these words, it sounds like they are plural.
shirts, suits, and fruits
My Japanese friend told me he had to buy a new スーツ.
I explained that 'a' means one, so he doesn't need it in this sentence. “I have to buy new suits” is correct.
"No, no!" He said. "I only need 1 new スーツ."
Ah! Okay, you should say "I want to buy a new suit."
スーツ sounds just like suits in English, so be careful! Suits means more than 1.
"My shirt is still at the dry cleaners." (One shirt)
"Eric eats fresh fruit everyday with his breakfast." (when we talk about fruit in general we don't need an S)