The Top 5 most widely spoken languages in the world and number of speakers are:

Chinese - 1,197,000,000

Spanish - 414,000,000

English - 335,000,000

Hindu - 260,000,000

Arabic-237,000,000

Chinese is a group of related, but in many cases mutually unintelligible, language varieties, forming a branch of the Sino-Tibetan language family. Chinese is spoken by the Han majority and many other ethnic groups in China. Nearly 1.2 billion people (around 16% of the world's population) speak some form of Chinese as their first language.

More Info: en.m.wikipedia.org