Questions & Answers about Портной пришил заплатку.
- Портной = tailor
- пришил = sewed on / attached by sewing
And заплатку is the object:
- заплатка = patch
- заплатку = patch in the accusative case
So the sentence is literally something like The tailor sewed on a patch.
Because портной is a masculine noun with a stem pattern that happens to end in -ой in the nominative singular.
This is normal in Russian. Not all masculine nouns end in a consonant. Some end in:
- a consonant, like стол
- -й, like герой
- and some adjective-like occupational words such as портной
So портной is still masculine singular, even though the ending may look unusual at first.