Learn Italian: Lei è bendata e annusa la scatola. - She is blindfolded and smells the box.

Annusare means to actively smell or sniff something. You use sapere di when an object emits a smell. If we wanted to describe what the box smells like, we would use the lesson's structure: la scatola sa di legno (the box smells like wood).

Could I use the verb sentire instead of annusare to say she smells the box?

You could say sente l'odore della scatola, but annusare is more precise here. Sentire is a general verb for perception (hearing, feeling, smelling). Annusare emphasizes the deliberate, physical action of sniffing to investigate something, which fits perfectly since she is blindfolded.

I've also seen the verb odorare. How does it fit in with annusare and sapere di?

Odorare can mean both to actively sniff (like annusare) and to emit a scent (like sapere di). Because it can be ambiguous, Italians generally prefer annusare for the active action of sniffing, and sapere di for describing what something smells like.

What is the noun behind the adjective bendata?