The Arabic language is the cultural language of the middle-east, in fact a lingua franca, and the language of diplomacy and social affairs in all Arabic countries. It has approximately 280 million native speakers along with about 250 million non-native speakers. Accordingly this is the fifth most spoken language in the world.
Arabic influenced many other languages, like Spanish, Portuguese, Hindi, Persian, Turkish, and more.
Moreover almost all languages has loanwords from Arabic. In English for example among others the following words are derived from Arabic: admiral, algebra, arsenal, elixir, camphor, coffee, magazine, massage, saffron, Satan, syrup, tariff, zenith.
In the middle ages, Arabic was cultural language, the carrier of encyclopedic knowledge, like French in the 18th century. Medicine, mathematics, astronomy, and philosophy was transfered by Arabic. Its cultural significance is well illustrated by the fact, that the Arabic word كتاب "book" is used in 15 different languages with the same meaning.
Arabic plays an important role also in studying Semitic languages, for it features enormous literature and vast amount of speakers for almost 3000 years until today. It has written lexicons and grammars long ago. It is a serious help in reconstruction and resuscitation of extinct Semitic languages like Ugaritic, Akkadian, and Hebrew.
And what's probably even more important, that Arabic is liturgical language, the language of a religion. The central language of Islam as well as other religions like Arab Christians, Arab Druze, Mizrahi Jews and Iraqi Mandaeans.
Arabic is the language of the Noble Qur'an and the records about the life of Prophet Muhammad.
Note: You may realized that the author of these posts are a non-native English speaker. I tried hard to avoid mistakes, but I apologize if they happened anyway. Nevertheless I welcome any correction in email.