Learn Spanish (Spain): No la llames más; estará conduciendo y no puede descolgar. - Don't call her anymore, she is probably driving and can't pick up.

This is the "epistemic future" or future of probability, which is exactly what this lesson is about! In Spanish, you can use the future continuous (estará + gerund) to express a guess or assumption about an action happening right now. So estará conduciendo translates to "she is probably driving" or "she must be driving".

What is the literal meaning of descolgar and why is it used for answering the phone?

Descolgar literally means "to un-hang" (des- + colgar). It comes from the days of older telephones where you literally had to lift the receiver off a physical hook to answer. In Spain, it remains a very standard, everyday verb for "picking up" a phone call, even on modern smartphones.

Why is it la llames instead of le llames? Isn't "her" the indirect object?

When llamar means "to phone someone", the person being called is actually the direct object. Therefore, you use the direct object pronoun la for a woman. While you might occasionally hear le llames in certain regions due to a phenomenon called leísmo, using the direct object la is the standard and grammatically correct choice.

Why is the verb form llames used instead of the normal imperative llama?