If using a broad definition of 'language', the fastest most understandable language used today is computer language. Written language on the internet is easily and quickly translated (though sometimes with errors).
If you mean spoken to written languages, English is the world's universal business language today.
Most experts believe immersion is the fastest way to learn any language.
The most dominant language spoken in the world today is English.
Mandarin Chinese is the most widely spoken language in the world today.
most of the language is french but there is some British language there to
Bantu
Chinese (Mandarin)
The fastest production four-stroke single cylinder motorcycle is most likely the 2011 Honda CBR250R.
In 1960, Spanish was the second most spoken language, just as it is today.
Spanish.
Realistic language is more understandable than flowery speech or dull textbook language. Most people would rather read a book written in "plain old English" instead of reading a lot of long words and fancy terms.
The fastest computers are constantly changing. Even if I knew the answer right now, I would be wrong next week. Most the fastest computers today are designed for high performance gaming from companies such as Alienware.
Probably the most widely spoken language in the world today is English. It has become a standard language for conducting business transactions. It has also become the language of the European common market. It is threatening to overwhelm a number of local languages. For example, in Central America there are 28 Maya Languages which are related but are not mutually understandable. Many of their speakers can not understand Spanish. They can pick up English on satellite. A number of their speakers want to leave behind their ways and join the modern world. They have chosen to learn English over Spanish. Thus the use of English is growing. There are other languages. The second most widely used language is Chinese.