"His shorts is nice"
Translation:Kaptura yake ni nzuri
Pluralia tantum are hard, so it's not surprising this would be wrong. Report it; it doesn't get fixed from the comments.
We could simplify the English language one day. "His pair of shorts is nice" is correct but we talking about only one garment here. In East African English the longer version is called a "trouser" and I like that name!