One of the unique features of Arabic is that all words have a root. for example all the words عالم، معلم، تعلیم، اعلام، علامه all share the same root of ع-ل-م.
In this example our root has only three letters
1 ع
2 ل
3 م
And then additional letters are added to it to make new words. In Arabic Most of the words you will come accross have three-letter roots حمد – سجد – عبد – خرج – خلق . But there are some four-letter and five-letter roots too.
Four letter root: ج-ع-ف-ر and د-ح-ر-ج
Five letter root: س-ف-ر-ج-ل