Learn Dutch: Wij zullen ons vandaag aan de baas voorstellen. - We will introduce ourselves to the boss today.

The verb here is zich voorstellen, which is a reflexive verb meaning "to introduce oneself". Since the subject is wij (we), the matching reflexive pronoun must be ons (ourselves).

Isn't voorstellen a separable verb? Why isn't it split up here?

You are right, it is a separable verb (voor + stellen). However, the helping verb zullen (will) pushes the main working verb to the very end of the sentence. When a separable verb gets pushed to the end like this, its parts stay glued together as a full infinitive.

I've learned that zich voorstellen means "to imagine". How do I know it means "introduce" here?

Zich voorstellen is a reflexive verb that can mean both "to introduce oneself" and "to imagine". The big clue here is the word aan (to). When you use this verb aan someone (like aan de baas), it means you are introducing yourself to them.

Why do we use aan for "to" instead of naar?

Naar is mostly used for physical travel toward a destination (like going to the supermarket). Aan is used when you are directing an action toward a recipient, such as giving something to someone, or in this case, introducing yourselves to the boss.