This is the 6311th most frequent Arabic word.
أنكم
"That you (plural)."
The word 'أنكم' in this sentence serves as part of a subordinate clause introducing what is believed, with 'أن' linking the clauses and 'كم' indicating the subject 'you (plural)'.
أعتقد أنكم تفهمون الدرس.
I believe that you (plural) understand the lesson.
Here, 'أنكم' is used in expressing a wish or hope, connecting the main clause with the one describing the wish and including a pronoun for the audience addressed.
أتمنى أنكم تصلون بأمان.
I hope that you (plural) arrive safely.
In this example, 'أنكم' introduces information that was heard, functioning as a conjunction and a point of tense consistency with the pronoun referring to the addressed group.