feminine   die Fahne flag   rot red           Man sah überall rote Fahnen. Everywhere red flags were to be seen.

Rote Fahnen is feminine plural. Die Fahne is direct of object (Accusative) in the German sentence. If we check the table we will see that the ending (a linguist would say the grammatical morpheme) is rote.

neutrum   das Obst fruit   frisch fresh           Auf dem Tisch stand frisches Obst. Fresh fruit stood on the table.

Frisches Obst is neutral, singular. Das Obst is direct object (Accusative). If we check the table we will see that the ending is -es and therefore the adjective is frisches.

masculine   der Anzug suit   blau blue           Blaue Anzüge stehen ihm nicht. Blue suits don't suit him.

Blaue Anzüge is masculine, plural. Blaue Anzüge is the subject of the phrase (= Nominative). If we check the table we will see that the ending is -e and therefore the adjective is blaue.