Breakdown of Señora, ¿necesita usted la maleta ahora?
ahora
now
la señora
the lady / madam (form of address)
usted
you (formal, singular)
necesitar
to need
Questions & Answers about Señora, ¿necesita usted la maleta ahora?
Why does the verb necesita look like "he/she needs" if the speaker is saying "you need"?
This is because of the formal "you", usted. Even though usted means "you", it always uses the exact same verb endings as "he" (él) and "she" (ella). Since "he needs" is necesita, "you need" (formal) is also necesita.
Why is usted placed right after the verb necesita?
In Spanish questions, it is very common to flip the normal word order and put the subject pronoun (usted) directly after the verb (necesita). You could actually drop usted entirely and just ask ¿necesita la maleta ahora?, but keeping it in the sentence makes it extra clear and polite.
Why use la maleta (the suitcase) instead of su maleta (your suitcase)?