The introduction of Arabic words into Spanish began in earnest in the eighth century, although even before then some words of Latin and Greek origin had roots in Arabic. People living in what is now Spain spoke Latin at one time, of course, but over the centuries Spanish and other Romance languages such as French and Italian gradually differentiated themselves. The Latin dialect that eventually became Spanish was highly influenced by the invasion of the Arabic-speaking Moors in 711. For many centuries, Latin/Spanish and Arabic existed side by side, and even today many Spanish place names retain Arabic roots. It wasn't until late in the 15th century that the Moors were expelled, and by then literally thousands of Arabic words had become part of Spanish.
Here, we can find some of the most common Arabic-origin Spanish words. Many of the words also are a part of English. Although it is believed that the English words "alfalfa" and "alcove," which originally were Arabic, entered English by way of Spanish (alfalfa and alcoba), most Arabic words in English probably entered English by other routes.
Keep in mind also that Arabic has changed substantially since the 15th century. Arabic words from then aren't necessarily in use today, or they may have changed meaning.