Many adjectives like 好 also function as verbs, so the verb 是 is not used as often in Chinese as the verb “to be” is used in English. Most of the times it is used when you have a statement of the form A=B (e.g. 我是 Adam).
Some countries have alternate names in Chinese just like they may have in English (e.g. Britain / England, Holland / the Netherlands etc.)
In general, nationalities can be derived from countries by adding a 人 at the end of the country.
E.g. 印度 becomes 印度人
Similarly, languages are also derived from the names of countries but in different ways:
• By adding a 文 after the name of the country.
E.g. 西班牙 becomes 西班牙文
• By adding a 文 after the first character in the name of the country
E.g. 日本 becomes 日文
• In some cases you will see 语 being used in place of 文
E.g. 台湾 becomes 台语