Tongan is the word you use for anything belonging to Tonga, the island country in the South Pacific. It works three ways.

Tongan Tongan is是 the word you use你用來指的詞 for anything belonging to Tonga「屬於東加」的, the island country in the South Pacific東加是南太平洋的一個島國。It works three ways它有三種用法。

As an adjective: 'Tongan food', 'the Tongan flag', 'a Tongan custom'.

As an adjective:當形容詞用: 'Tongan food', 'the Tongan flag', 'a Tongan custom''Tongan food'（東加食物）、'the Tongan flag'（東加國旗）、'a Tongan custom'（東加的習俗）。

As a noun for a person: 'He is a Tongan', or more often 'Tongans are known for being big rugby players' — this is the normal way to talk about the people.

As a noun for a person:當指人的名詞用: 'He is a Tongan','He is a Tongan'他是東加人 or more often 'Tongans are known for being big rugby players' —或更常見的 'Tongans are known for being big rugby players'東加人以體格壯碩的橄欖球員聞名— this is the normal way to talk about the people這是講到這群人時最正常的說法。

And as the name of the language: 'She speaks Tongan at home with her grandmother.' Tongan the language is a Polynesian language, so it is a cousin of Hawaiian, Samoan and Maori, not related to English at all.

And as the name of the language:還可以當語言名稱用: 'She speaks Tongan at home with her grandmother.''She speaks Tongan at home with her grandmother.'她在家跟祖母講東加語。Tongan the language is a Polynesian language,東加語是玻里尼西亞語系的語言 so it is a cousin of Hawaiian, Samoan and Maori,跟夏威夷語、薩摩亞語、毛利語是親戚 not related to English at all跟英文完全沒有關係。

One useful habit in English: when you talk about the language, you use no 'the' and no plural — 'I am learning Tongan', never 'the Tongan' or 'Tongans' for the language.

One useful habit in English:有個英文的實用小習慣: when you talk about the language,講到這個語言時 you use no 'the' and no plural —不加 'the'，也不用複數— 'I am learning Tongan','I am learning Tongan' never 'the Tongan' or 'Tongans' for the language絕不會說 'the Tongan' 或 'Tongans' 來指語言。