Quotations from the Works of Mao Tse-tung is the second most widely read book in the world. It is commonly known as the Little Red Book. There have been 820 million copies sold in the last 50 years.
The Diary of Anne Frank
The Lord of the Rings. By J.R.R. Tolkien, is the second most read book in the English Language. But considering populations I would expect the second most read book in the entire world would be one of three. The Bible. The Bhagavad Gita. Or the Koran. The Bible actually if you take the facts into account.
The Bible is by far the most widely purchased book.
The New England Primer
English is the most widely used second language in the world. It is an official or widely spoken language in many countries, and is commonly used as a lingua franca for international communication in business, tourism, and diplomacy.
Bengali
English is the language most spoken as their second language.
Cantonese dialect is the second most widely used language in China.
If you are asking what the second most spoken language in the world is, by number of total speakers, it's English. If you are asking what the second most widely spoken language is, it's Spanish. If you are asking what language is the most common second language for people, it's English.
The most widely read and studied book of the renaissance was the Baldassare Castiglione.
Spanish is the second most widely spoken language in the world by number of native speakers, following Mandarin Chinese. It is also a major international language, with a large number of non-native speakers.
German is the second most widely spoken Germanic language. (English is the most widely spoken Germanic language.)