Learn Farsi: جنس این لباس عالی است، چه مخمل باشد چه ابریشم. - The material of this dress is excellent, whether it is velvet or silk.

The structure che [A] ... che [B] ... translates to "whether [A] or [B]". It is used to show that the main statement (the dress being excellent) remains true regardless of which of the two conditions (velvet or silk) applies.

Why is the verb bashad in the subjunctive mood here?

The subjunctive is used because the exact material of the dress is presented as a hypothetical or uncertain possibility. When you use che ... che ... to say "whether it be this or that", the verb attached to those options must be in the subjunctive.

Why is there no verb after che abrisham?

In Persian, when the exact same verb applies to both parts of a paired structure like che ... che ..., the second verb is usually dropped to avoid repetition. Saying che makhmal bashad che abrisham bashad is grammatically fine, but dropping the second bashad sounds much more natural.

I learned that jens means "gender". Why is it translated as "material" here?

The word jens is versatile and can mean "gender", "type", "goods", or "material" depending on what you are talking about. When describing physical objects like lebas (clothes) alongside fabrics like makhmal (velvet), it always refers to the physical material or quality.