Jocular colloquial expression used in place of だ when mimicking or attributing speech to a Chinese person; possibly from Manchukuo pidgin. Not standard Japanese.
"This is very delicious, you know," he said jokingly, using the stereotyped Chinese-character speech pattern.
漫画では、中国人キャラが「〜アル」と話すことがある。
In manga, Chinese characters sometimes speak using "〜アル".