Learn Spanish (Spain): La bibliotecaria está trayendo los poemas.

Trayendo is the gerund (the -ing form) of the verb traer (to bring). Normally, you take off the -er and add -iendo. But if you do that to traer, you get traiendo, which puts an unaccented 'i' between the vowels 'a' and 'e'. In Spanish, an unaccented 'i' between two vowels always changes to a 'y', making it trayendo.

Why does this sentence use está trayendo instead of just trae?

This sentence uses the present continuous tense (the verb estar plus the gerund) to emphasize that the action is happening right at this very moment. If you use the simple present (La bibliotecaria trae los poemas), it can mean she is bringing them right now, but it often means she brings them regularly. Está trayendo leaves no doubt that the action is currently in progress.

Wait, why is it los poemas? Doesn't the -a at the end make it feminine?

Usually, yes! But many Spanish words that end in -ma are actually masculine. That is why it is el poema in the singular and los poemas in the plural. You will see this rule in other common words you have learned like el problema and el idioma.