Learn Spanish (Latin America): El apicultor debe usar el velo para evitar las picaduras. - The beekeeper must wear the veil to avoid stings.

The verb deber followed directly by an infinitive expresses a strict obligation or necessity, meaning the beekeeper is required to wear the veil. If it were debe de usar, it would express an assumption or high probability, changing the meaning to something like he must be wearing the veil right now because I hear bees buzzing.

Why do we need the article las in evitar las picaduras when the English translation just says to avoid stings?

Spanish requires definite articles like el or las when talking about things in a general sense. Since the beekeeper wants to avoid stings as a general category of things rather than specific, previously mentioned stings, las picaduras is required.

Could I use para que instead of para to say to avoid?

Not in this exact sentence. You use para plus the infinitive evitar because the person who must wear the veil is the exact same person who is avoiding the stings. You only use para que with a conjugated subjunctive verb when there is a change of subject.

Is usar the only way to say to wear in this context?

You could also use llevar or llevar puesto. However, usar is extremely common in Latin America for wearing clothing or accessories, and it works especially well here because a veil is a piece of functional safety equipment.